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<!DOCTYPE html><html><head><meta charset="utf-8"><title>Array JavaScript API</title><meta name="description" content="Interactive API reference for the JavaScript Array Object. Arrays are containers that allow access to its items through numerical indices."><link rel="stylesheet" type="text/css" href="styles.css"><script type="text/javascript">var _gaq = _gaq || [];
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}</script><div class="topnav"><a href="/">JavaScripture</a><div class="bookmarks"><a class="bookmark contribute" href="https://github.com/nkronlage/JavaScripture">Contribute via GitHub</a> <a class="bookmark" href="/feedback">Feedback</a></div></div><div class="container"><nav class="leftnav"><div id="searchContainer"><input id="searchBox" type="text" placeholder="Search (Ctrl + S)" autocomplete="false"><div id="resultsBox" style="display:none;"></div></div><div id="apichooser"><a href="#" onclick="openApiChooser(); return false;"><div class="arrow"></div><span id="selectedsets"></span></a><div id="obscure"></div><div id="apisets"><ul></ul></div></div><div class="toc"><h2>Array</h2><div class="navgroup"><div class="group"><a href="#Constructors">Constructors</a></div><div class="group"><a href="#InstanceIndexers">Instance Indexers</a></div><div class="group collapsed"><a href="#InstanceProperties" onclick="expandoClicked(this.parentNode); return false;"><div class="arrow"></div>Instance Properties</a><div class="subgroup"><a href="#length">length</a></div></div><div class="group collapsed"><a href="#InstanceMethods" onclick="expandoClicked(this.parentNode); return false;"><div class="arrow"></div>Instance Methods</a><div class="subgroup"><a href="#concat_Object_Object_dotdotdot">concat</a><a href="#copyWithin_Number_Number_Number">copyWithin</a><a href="#entries_">entries</a><a href="#every_Function_Object">every</a><a href="#fill_Object_Number_Number">fill</a><a href="#filter_Function_Object">filter</a><a href="#find_Function_Object">find</a><a href="#findIndex_Function_Object">findIndex</a><a href="#flat_Number">flat</a><a href="#flatMap_Function_Object">flatMap</a><a href="#forEach_Function_Object">forEach</a><a href="#includes_Object_Number">includes</a><a href="#indexOf_Object_Number">indexOf</a><a href="#join_String">join</a><a href="#keys_">keys</a><a href="#lastIndexOf_Object_Number">lastIndexOf</a><a href="#map_Function_Object">map</a><a href="#pop_">pop</a><a href="#push_Object_Object_dotdotdot">push</a><a href="#reduce_Function_Object">reduce</a><a href="#reduceRight_Function_Object">reduceRight</a><a href="#reverse_">reverse</a><a href="#shift_">shift</a><a href="#slice_Number_Number">slice</a><a href="#some_Function_Object">some</a><a href="#sort_Function">sort</a><a href="#splice_Number_Number_Object_Object_dotdotdot">splice</a><a href="#unshift_Object_Object_dotdotdot">unshift</a><a href="#values_">values</a></div></div><div class="group collapsed"><a href="#ArrayMethods" onclick="expandoClicked(this.parentNode); return false;"><div class="arrow"></div>Array Methods</a><div class="subgroup"><a href="#from">from</a><a href="#isArray_Object">isArray</a><a href="#of_Object_Object_dotdotdot">of</a></div></div></div><h2>JavaScript API</h2><div id="related-apis" class="navgroup"></div><h2>All API</h2><div id="rootObjs" class="navgroup"><span class="empty">No API set selected.</span></div></div></nav><div class="content"><h1 class="declaration"><span class="object">Array</span> <span class="type">: <a href="/Object">Object</a></span></h1><div class="metadata"><span>constructor</span> <span>iterable</span></div><div class="objectdescription">Arrays are containers that allow access to its items through numerical indices.<div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4" class="spec">Spec</a></div></div><div><a name=""></a><h2></h2><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="Array"></a> <a name="Array_"></a><div class="declaration"><span class="membername primary">Array</span>() : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Same as <a href="#new_Array"><code>new Array()</code></a>.</p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.1" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="Array"></a> <a name="Array_Number"></a><div class="declaration"><span class="membername primary">Array</span>(<span class="membername">length</span> : <a class="membertype" href="/Number">Number</a>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Same as <a href="#new_Array_Number"><code>new Array(length)</code></a>.</p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.1.1" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="Array"></a> <a name="Array_Object_Object_dotdotdot"></a><div class="declaration"><span class="membername primary">Array</span>(<span class="membername">item0</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">item1</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">...</span>]</span>]</span>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Same as <a href="#new_Array_Object_Object_dotdotdot"><code>new Array(item0, item1, ...)</code></a>.</p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.1.1" class="spec">Spec</a></div></div></div></div><div><a name="Constructors"></a><h2>Constructors</h2><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="Array"></a> <a name="new_Array"></a><div class="declaration">new <span class="membername primary">Array</span>() : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Creates an empty <code>Array</code> (<code>length</code> = 0). Can also be constructed as <code>[]</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
// The following are equivalent
var x = [];
var y = Array();
var z = new Array();
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.Array"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.2" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="Array"></a> <a name="new_Array_Number"></a><div class="declaration">new <span class="membername primary">Array</span>(<span class="membername">length</span> : <a class="membertype" href="/Number">Number</a>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Creates an <code>Array</code> of the specified length where each item starts as <code>undefined</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var squares = Array(5);
for (var i = 0; i < squares.length; i++) {
squares[i] = i * i;
}
console.log('squares = ' + squares);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.Array"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.2.1" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="Array"></a> <a name="new_Array_Object_Object_dotdotdot"></a><div class="declaration">new <span class="membername primary">Array</span>(<span class="membername">item0</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">item1</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">...</span>]</span>]</span>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Creates an <code>Array</code> with the specified parameters as the 0th, 1st, ... items of the <code>Array</code>. Can also be constructed as <code>[item0, item1, ...]</code>. See also <a href="#of"><code>Array.of()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
// The following are equivalent
var x = ['a', 'b', 'c'];
var y = Array('a', 'b', 'c');
var z = new Array('a', 'b', 'c');
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.Array"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.2.1" class="spec">Spec</a></div></div></div></div><div><a name="InstanceIndexers"></a><h2>Instance Indexers</h2><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="indexer_Number"></a><div class="declaration"><span class="membername primary">this</span>[<span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>] : <a class="membertype" href="/Object">Object</a></div><div class="member-body"><p class="description">Gets and sets the item in <code>this</code> at <code>index</code>. <code>index</code> should be between <code>0</code> and <code><a href="#length">this.length</a> - 1</code>. If setting to an index greater than <code>length - 1</code>, <code>length</code> will be increased to <code>index + 1</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c'];
for (var i = 0; i < x.length; i++) {
console.log(x[i]);
}
console.log(x.length);
x[7] = 'h';
console.log(x[7]);
console.log(x.length);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.undefined"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p></div></div></div><div><a name="InstanceProperties"></a><h2>Instance Properties</h2><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="length"></a><div class="declaration"><span class="membername primary">length</span> : <a class="membertype" href="/Number">Number</a></div><div class="member-body"><p class="description">The number of items in <code>this</code>. It is 1 greater than the index of the last item. Setting <code>length</code> to a smaller number than the current <code>length</code> will remove elements from the end of the list.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
console.log([].length);
console.log(['a', 'b', 'c'].length);
console.log(Array(100).length);
var x = [];
// Assigning to an index automatically adjusts length
x[50] = 'foo';
console.log(x.length);
// Set length to 0 to clear the list.
x.length = 0;
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.length"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.5.2" class="spec">Spec</a></div></div></div></div><div><a name="InstanceMethods"></a><h2>Instance Methods</h2><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="concat"></a> <a name="concat_Object_Object_dotdotdot"></a><div class="declaration"><span class="membername primary">concat</span>(<span class="membername">item0</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">item1</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">...</span>]</span>]</span>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Returns a new Array composed of the items of <code>this</code> followed by <code>item0, item1, ...</code>. If any of the parameters are Arrays themselves, the values of that Array will be concatenated into the new Array. See also <a href="#push">push</a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = [1, 2, 3];
var concatenated = x.concat(4, 5, [6, 7]);
console.dir(concatenated);
console.log(concatenated.length);
console.dir(x); // x is unchanged
// The spread operator (...) also allows concatenating.
var spread = [...x, 4, 5, ...[6, 7]];
console.dir(spread);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.concat"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.4" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="copyWithin"></a> <a name="copyWithin_Number_Number_Number"></a><div class="declaration"><span class="membername primary">copyWithin</span>(<span class="membername">target</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">start</span> : <a class="membertype" href="/Number">Number</a>, <span class="optional">[<span class="membername">end</span> : <a class="membertype" href="/Number">Number</a>]</span>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Copies <code>this[start], this[start + 1], ... this[end - 1]</code> to <code>this[target], this[target + 1], ... this[target + start - end - 1]</code>. If <code>end</code> is not specified, <code>this.length</code> will be used. If <code>end</code> is greater than <code>this.length</code>, it is clamped to <code>this.length</code>. Note, no elements are copied past <code>this.length - 1</code> (ie, <code>copyWithin()</code> will not increase the length of <code>this</code>). Returns <code>this</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c', 'd', 'e', 'f'];
// Copy elements at end to the beginning
console.log(x.copyWithin(0, 3));
x = ['a', 'b', 'c', 'd', 'e', 'f'];
// Copy elements at the beginning to the end
console.log(x.copyWithin(3, 0));
x = ['a', 'b', 'c', 'd', 'e', 'f'];
// Copy first 3 elements to middle
console.log(x.copyWithin(2, 0, 3));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.copyWithin"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.prototype.copywithin" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="entries"></a> <a name="entries_"></a><div class="declaration"><span class="membername primary">entries</span>() : <a class="membertype" href="/Iterator">Iterator</a><<a class="membertype" href="/Array">Array</a>></div><div class="member-body"><p class="description">Returns an iterator of the index and items in <code>this</code> where the <a href="Iterator#next"><code>value</code>s</a> of the iterator are of the form <code>[index : <a href="/Number">Number</a>, item : <a href="/Object">Object</a>]</code>. See also <a href="#values"><code>values()</code></a> and <a href="#keys"><code>keys()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b'];
// Use for (... of ...) to loop over the iterator
for (var entry of x.entries()) {
console.dir(entry);
}
// Or access the iterator manually
var entries = x.entries();
console.dir(entries.next());
console.dir(entries.next());
console.dir(entries.next());
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.entries"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.prototype.entries" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="every"></a> <a name="every_Function_Object"></a><div class="declaration"><span class="membername primary">every</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/Boolean">Boolean</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/Boolean">Boolean</a></div></div><div class="member-body"><p class="description">Returns <code>true</code> if <code>callback</code> returns <code>true</code> for every item in <code>this</code>. Otherwise returns <code>false</code>. The <code>Array</code> passed to <code>callback</code> is the <code>this</code> of the call to <code>every</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var isEven = function(x) { return (x % 2) === 0; }
console.log([2, 22, 36].every(isEven));
console.log([6, 19, 18].every(isEven));
console.log([5, 19, 17].every(isEven));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.every"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.16" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="fill"></a> <a name="fill_Object_Number_Number"></a><div class="declaration"><span class="membername primary">fill</span>(<span class="membername">value</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">start</span><span class="defaultvalue"> = 0</span> : <a class="membertype" href="/Number">Number</a>, <span class="optional">[<span class="membername">end</span> : <a class="membertype" href="/Number">Number</a>]</span>]</span>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Fills <code>this[start]</code>, <code>this[start + 1]</code>, ... <code>this[end - 1]</code> with <code>value</code>. If <code>end</code> is not specified, <code>this.length</code> is used. Returns <code>this</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = Array(5);
console.log(x.fill('a'));
console.log(x.fill('b', 3));
console.log(x.fill('c', 0, 2));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.fill"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.prototype.fill" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="filter"></a> <a name="filter_Function_Object"></a><div class="declaration"><span class="membername primary">filter</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/Array">Array</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/Boolean">Boolean</a></div></div><div class="member-body"><p class="description">Returns a new <code>Array</code> containing only the items in <code>this</code> that <code>callback</code> returned <code>true</code> for. The <code>Array</code> passed to <code>callback</code> is the <code>this</code> of the call to <code>filter</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var isEven = function(x) { return (x % 2) === 0; }
var numbers = [1, 2, 4, 5, 7, 9, 12];
console.log(numbers.filter(isEven));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.filter"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.20" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="find"></a> <a name="find_Function_Object"></a><div class="declaration"><span class="membername primary">find</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/Object">Object</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/Boolean">Boolean</a></div></div><div class="member-body"><p class="description">Returns the first item in <code>this</code> where <code>callback</code> returns <code>true</code> for that item. The <code>Array</code> passed to <code>callback</code> is the <code>this</code> of the call to <code>find</code>. See also <a href="#findIndex"><code>findIndex()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'foo', 'd', 'e'];
console.log(x.find(function(item) {
return item.length > 1;
}));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.find"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.prototype.find" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="findIndex"></a> <a name="findIndex_Function_Object"></a><div class="declaration"><span class="membername primary">findIndex</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/Number">Number</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/Boolean">Boolean</a></div></div><div class="member-body"><p class="description">Returns the index of the first item in <code>this</code> where <code>callback</code> returns <code>true</code> for that item. See also <a href="#find"><code>find()</code></a> and <a href="#indexOf"><code>indexOf()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'foo', 'd', 'e'];
console.log(x.findIndex(function(item) {
return item.length > 1;
}));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.findIndex"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.prototype.findIndex" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="flat"></a> <a name="flat_Number"></a><div class="declaration"><span class="membername primary">flat</span>(<span class="optional">[<span class="membername">depth</span><span class="defaultvalue"> = 1</span> : <a class="membertype" href="/Number">Number</a>]</span>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Returns a new Array by flattening sub arrays into the array up to the specified <code>depth</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = [1, [2, 3], 4, [5, 6, [7, 8], 9]];
console.dir(x);
console.dir(x.flat());
console.dir(x.flat(2));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.flat"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2019">ECMAScript 2019</span> <a href="https://tc39.es/ecma262/#sec-array.prototype.flat" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="flatMap"></a> <a name="flatMap_Function_Object"></a><div class="declaration"><span class="membername primary">flatMap</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/Array">Array</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/Object">Object</a></div></div><div class="member-body"><p class="description">Returns a new <code>Array</code> with where each item is the result of calling <code>callback</code> on each item in <code>this</code>. If the return of <code>callback</code> is an Array, that Array will be flattened into the Array returned by <code>flatMap</code>. See also <a href="#map"><code>map()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = [1, 2, 3];
var callback = (i, index) => [i, i * index];
var y = x.flatMap(callback);
console.dir(y);
// flatMap is essentially equivalent to:
var z = x.map(callback).flat();
console.dir(z);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.flatMap"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2019">ECMAScript 2019</span> <a href="https://tc39.es/ecma262/#sec-array.prototype.flatmap" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="forEach"></a> <a name="forEach_Function_Object"></a><div class="declaration"><span class="membername primary">forEach</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/undefined">undefined</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/undefined">undefined</a></div></div><div class="member-body"><p class="description">Calls <code>callback</code> for each item in <code>this</code>. The <code>Array</code> passed to <code>callback</code> is the <code>this</code> of the call to <code>forEach</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c'];
x.forEach(function(item, index) {
console.log('item at ' + index + ' = ' + item);
});
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.forEach"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.18" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="includes"></a> <a name="includes_Object_Number"></a><div class="declaration"><span class="membername primary">includes</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">startingIndex</span><span class="defaultvalue"> = 0</span> : <a class="membertype" href="/Number">Number</a>]</span>) : <a class="membertype" href="/Boolean">Boolean</a></div><div class="member-body"><p class="description">Returns <code>true</code> if <code>item</code> is an element of <code>this</code> starting the search from <code>startingIndex</code>. If <code>startingIndex</code> is negative, <code>this.length</code> is added to it before starting the search.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c', 'd'];
console.log(x.includes('b'));
console.log(x.includes('b', 2));
console.log(x.includes('a', -2));
console.log(x.includes('e'));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.includes"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2016">ECMAScript 2016</span> <a href="http://www.ecma-international.org/ecma-262/7.0/#sec-array.prototype.includes" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="indexOf"></a> <a name="indexOf_Object_Number"></a><div class="declaration"><span class="membername primary">indexOf</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">startingIndex</span><span class="defaultvalue"> = 0</span> : <a class="membertype" href="/Number">Number</a>]</span>) : <a class="membertype" href="/Number">Number</a></div><div class="member-body"><p class="description">Returns the first location of <code>item</code> in <code>this</code> starting the search from <code>start</code>. If <code>startingIndex</code> is negative, <code>this.length</code> is added to it before starting the search. Returns <code>-1</code> if <code>item</code> is not found. See also <a href="#findIndex"><code>findIndex()</code></a> and <a href="#lastIndexOf"><code>lastIndexOf()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c', 'd', 'b', 'c', 'a'];
console.log(x.indexOf('b'));
console.log(x.indexOf('b', 2));
console.log(x.indexOf('b', -4));
console.log(x.indexOf('e', 2));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.indexOf"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.14" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="join"></a> <a name="join_String"></a><div class="declaration"><span class="membername primary">join</span>(<span class="optional">[<span class="membername">separator</span><span class="defaultvalue"> = ','</span> : <a class="membertype" href="/String">String</a>]</span>) : <a class="membertype" href="/String">String</a></div><div class="member-body"><p class="description">Returns a String created by joining the <code>toString()</code> of each item of <code>this</code> separated by <code>separator</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c'];
console.log(x.join());
console.log(x.join(' -- '));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.join"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.5" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="keys"></a> <a name="keys_"></a><div class="declaration"><span class="membername primary">keys</span>() : <a class="membertype" href="/Iterator">Iterator</a><<a class="membertype" href="/Number">Number</a>></div><div class="member-body"><p class="description">Returns an iterator of the indicies in <code>this</code>. See also <a href="#entries"><code>entries()</code></a> and <a href="#values"><code>values()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b'];
// Use for (... of ...) to loop over the iterator
for (var key of x.keys()) {
console.dir(key);
}
// Or access the iterator manually
var keys = x.keys();
console.dir(keys.next());
console.dir(keys.next());
console.dir(keys.next());
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.keys"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.prototype.keys" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="lastIndexOf"></a> <a name="lastIndexOf_Object_Number"></a><div class="declaration"><span class="membername primary">lastIndexOf</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">startingIndex</span> : <a class="membertype" href="/Number">Number</a>]</span>) : <a class="membertype" href="/Number">Number</a></div><div class="member-body"><p class="description">Returns the location of <code>item</code> by searchig backwards through <code>this</code>, starting the search from <code>startingIndex</code>. If <code>startingIndex</code> is not specified, the search starts from the end of the array. If <code>startingIndex</code> is negative, <code>this.length</code> is added to it before starting the search. Returns <code>-1</code> if <code>item</code> is not found. See also <a href="#indexOf"><code>indexOf()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c', 'd', 'b', 'c', 'a'];
console.log(x.lastIndexOf('b'));
console.log(x.lastIndexOf('b', 3));
console.log(x.lastIndexOf('b', -4));
console.log(x.lastIndexOf('e', 2));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.lastIndexOf"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.15" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="map"></a> <a name="map_Function_Object"></a><div class="declaration"><span class="membername primary">map</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/Array">Array</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/Object">Object</a></div></div><div class="member-body"><p class="description">Returns a new <code>Array</code> with where each item is the result of calling <code>callback</code> on each item in <code>this</code>. The <code>Array</code> passed to <code>callback</code> is the <code>this</code> of the call to <code>map</code>. See also <a href="#flatMap"><code>flatMap()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var numbers = [1, 2, 3, 4];
var squares = numbers.map(function(x) { return x * x; });
console.log(squares);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.map"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.19" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="pop"></a> <a name="pop_"></a><div class="declaration"><span class="membername primary">pop</span>() : <a class="membertype" href="/Object">Object</a></div><div class="member-body"><p class="description">Removes the last item from <code>this</code> and returns the removed item. Returns <code>undefined</code> if <code>this</code> is empty. Use with <a href="#push"><code>push</code></a> to treat an <code>Array</code> as a stack.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c'];
console.log(x.pop());
console.log(x);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.pop"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.6" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="push"></a> <a name="push_Object_Object_dotdotdot"></a><div class="declaration"><span class="membername primary">push</span>(<span class="membername">item0</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">item1</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">...</span>]</span>]</span>) : <a class="membertype" href="/Number">Number</a></div><div class="member-body"><p class="description">Appends the specified items to the end of <code>this</code> and returns the new value of <code>this.length</code>. Use with <a href="#pop"><code>pop</code></a> to treat an <code>Array</code> as a stack.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c'];
console.log(x.push('d', 'e'));
console.log(x);
// Use with the spread operator (...) to push all elements of an array
var y = ['x', 'y', 'z'];
x.push(...y);
console.log(x);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.push"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.7" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="reduce"></a> <a name="reduce_Function_Object"></a><div class="declaration"><span class="membername primary">reduce</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">initialValue</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/Object">Object</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">previous</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">current</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/Object">Object</a></div></div><div class="member-body"><p class="description">Calls <code>callback</code> for each item in <code>this</code> in ascending order (<code>0</code> to <code>length-1</code>). It passes the return value of <code>callback</code> for the <code>i-1</code>th item as the <code>previous</code> parameter for the <code>i</code>th item. Returns the result from the last call to <code>callback</code>. If <code>initialValue</code> is not specified, <code>callback</code> will first be called on <code>this[1]</code> with <code>previous</code> set to <code>this[0]</code>. The <code>Array</code> passed to <code>callback</code> is the <code>this</code> of the call to <code>reduce</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var join = function(prev, cur) { return prev + cur; }
console.log(['b', 'c'].reduce(join, 'a'));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.reduce"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.21" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="reduceRight"></a> <a name="reduceRight_Function_Object"></a><div class="declaration"><span class="membername primary">reduceRight</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">initialValue</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/Object">Object</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">previous</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">current</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/Object">Object</a></div></div><div class="member-body"><p class="description">Calls <code>callback</code> for each item in <code>this</code> in descending order (<code>length-1</code> to <code>0</code>). It passes the return value of <code>callback</code> for the <code>i+1</code>th item as the <code>previous</code> parameter for the <code>i</code>th item. Returns the result from the last call to <code>callback</code>. If <code>initialValue</code> is not specified, <code>callback</code> will first be called on <code>this[this.length - 2]</code> with <code>previous</code> set to <code>this[this.length - 1]</code>. The <code>Array</code> passed to <code>callback</code> is the <code>this</code> of the call to <code>reduceRight</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var join = function(prev, cur) { return prev + cur; }
console.log(['b', 'c'].reduceRight(join, 'a'));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.reduceRight"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.22" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="reverse"></a> <a name="reverse_"></a><div class="declaration"><span class="membername primary">reverse</span>() : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Reverses the order of the items in <code>this</code> and returns <code>this</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c'];
console.log(x.reverse());
console.log(x);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.reverse"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.8" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="shift"></a> <a name="shift_"></a><div class="declaration"><span class="membername primary">shift</span>() : <a class="membertype" href="/Object">Object</a></div><div class="member-body"><p class="description">Removes the first item of <code>this</code> and shifts the remaining items down by <code>1</code>. Returns the removed item.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c'];
console.log(x.shift());
console.log(x);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.shift"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.9" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="slice"></a> <a name="slice_Number_Number"></a><div class="declaration"><span class="membername primary">slice</span>(<span class="membername">start</span> : <a class="membertype" href="/Number">Number</a>, <span class="optional">[<span class="membername">end</span> : <a class="membertype" href="/Number">Number</a>]</span>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Returns a new <code>Array</code> which is composed of the items <code>this[start], this[start + 1], ..., this[end - 1]</code>. Note that <code>item[end]</code> is not included. If <code>start</code> or <code>end</code> is negative, the value is added to <code>this.length</code> before performing the slice. If <code>end</code> is not specified, <code>this.length</code> is used.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c', 'd', 'e'];
console.log(x.slice(2));
console.log(x.slice(2, 3));
console.log(x.slice(1, -2));
console.log(x.slice(-4, -1));
console.log(x);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.slice"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.10" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="some"></a> <a name="some_Function_Object"></a><div class="declaration"><span class="membername primary">some</span>(<span class="membername">callback</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>) : <a class="membertype" href="/Boolean">Boolean</a><div class="subfunction"><span class="membername">callback</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">array</span> : <a class="membertype" href="/Array">Array</a>) : <a class="membertype" href="/Boolean">Boolean</a></div></div><div class="member-body"><p class="description">Returns <code>true</code> if <code>callback</code> returns <code>true</code> for at least one item in <code>this</code>. Otherwise returns <code>false</code>. The <code>Array</code> passed to <code>callback</code> is the <code>this</code> of the call to <code>some</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var isEven = function(x) { return (x % 2) === 0; }
console.log([2, 22, 36].some(isEven));
console.log([6, 19, 18].some(isEven));
console.log([5, 19, 17].some(isEven));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.some"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.17" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="sort"></a> <a name="sort_Function"></a><div class="declaration"><span class="membername primary">sort</span>(<span class="optional">[<span class="membername">comparisonFunction</span> : <a class="membertype" href="/Function">Function</a>]</span>) : <a class="membertype" href="/Array">Array</a><div class="subfunction"><span class="membername">comparisonFunction</span>(<span class="membername">x</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">y</span> : <a class="membertype" href="/Object">Object</a>) : <a class="membertype" href="/Number">Number</a></div></div><div class="member-body"><p class="description">Sort the items of <code>this</code> using <code>comparisonFunction</code> to determine the sort order and returns <code>this</code>. The Number returned by <code>comparisonFunction</code> should be <code>0</code> if <code>x</code> and <code>y</code> are equal, negative if <code>x</code> is less than <code>y</code>, or positive if <code>x</code> is greater than <code>y</code>. If <code>comparisonFunction</code> is not specified, the <code>toString()</code> of the items will be sorted in alphanumeric order. Returns <code>this</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = [52, 7, 14, 22, 9];
// Sort alphanumerically
console.log(x.sort());
console.log(x);
// Sort numerically
var numericComparison = function(x, y) {
return x - y;
};
console.log(x.sort(numericComparison));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.sort"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.11" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="splice"></a> <a name="splice_Number_Number_Object_Object_dotdotdot"></a><div class="declaration"><span class="membername primary">splice</span>(<span class="membername">start</span> : <a class="membertype" href="/Number">Number</a>, <span class="membername">count</span> : <a class="membertype" href="/Number">Number</a>, <span class="optional">[<span class="membername">item0</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">item1</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">...</span>]</span>]</span>]</span>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Removes <code>count</code> items from <code>this</code> starting at index <code>start</code>. If the optional <code>items</code> are specified, they are inserted into <code>this</code> at <code>start</code>. Returns a new <code>Array</code> containing the removed items.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b', 'c', 'd', 'e'];
console.log(x.splice(2, 1));
console.log(x);
console.log(x.splice(1, 2, 'X', 'Y', 'Z'));
console.log(x);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.splice"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.12" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="unshift"></a> <a name="unshift_Object_Object_dotdotdot"></a><div class="declaration"><span class="membername primary">unshift</span>(<span class="membername">item0</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">item1</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">...</span>]</span>]</span>) : <a class="membertype" href="/Number">Number</a></div><div class="member-body"><p class="description">Inserts the specified items at the start of <code>this</code>. Returns the new value of <code>this.length</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['c', 'd', 'e'];
console.log(x.unshift('a', 'b'));
console.log(x);
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.unshift"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.13" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="values"></a> <a name="values_"></a><div class="declaration"><span class="membername primary">values</span>() : <a class="membertype" href="/Iterator">Iterator</a></div><div class="member-body"><p class="description">Returns an iterator of the items in <code>this</code>. The <code>values</code> function is also returned for <code>this[<a href="/Symbol#iterator">Symbol.iterator</a>]</code> so you can iterate over <code>this</code> directly to get the values. See also <a href="#entries"><code>entries()</code></a> and <a href="#keys"><code>keys()</code></a>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var x = ['a', 'b'];
// values is returned by x[Symbol.iterator] so you can just
// use x directly in the for (... of ...) loop
for (var value of x) {
console.dir(value);
}
// You can iterate over values explicitly
for (var value of x.values()) {
console.dir(value);
}
// Or access the iterator manually
var values = x.values();
console.dir(values.next());
console.dir(values.next());
console.dir(values.next());
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.values"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.prototype.values" class="spec">Spec</a></div></div></div></div><div><a name="ArrayMethods"></a><h2>Array Methods</h2><div class="methodgroup"><a name="from"></a> <span class="membername primary">from</span> 2 variants<div class="mode"><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="from_Object_Function_Object"></a><div class="declaration"><span class="membername primary">from</span>(<span class="membername">arrayLike</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">mapFunction</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>]</span>) : <a class="membertype" href="/Array">Array</a><div class="subfunction"><span class="membername">mapFunction</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>) : <a class="membertype" href="/Object">Object</a></div></div><div class="member-body"><p class="description">Returns a new <code>Array</code> with the elements of <code>arrayLike</code>. <code>from()</code> will return a new <code>Array</code> of length <code>arrayLike.length</code> where the elements are <code>arrayLike[0]</code>, <code>arrayLike[1]</code>, ..., <code>arrayLike[arrayLike.length - 1]</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
// From a string
console.log(Array.from('foo'));
// With a map function
var mapFunction = function(value) {
return value.toUpperCase();
};
console.log(Array.from('foo', mapFunction));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.from"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.from" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="from_Iterator_Function_Object"></a><div class="declaration"><span class="membername primary">from</span>(<span class="membername">iterator</span> : <a class="membertype" href="/Iterator">Iterator</a>, <span class="optional">[<span class="membername">mapFunction</span> : <a class="membertype" href="/Function">Function</a>, <span class="optional">[<span class="membername">thisArg</span> : <a class="membertype" href="/Object">Object</a>]</span>]</span>) : <a class="membertype" href="/Array">Array</a><div class="subfunction"><span class="membername">mapFunction</span>(<span class="membername">item</span> : <a class="membertype" href="/Object">Object</a>, <span class="membername">index</span> : <a class="membertype" href="/Number">Number</a>) : <a class="membertype" href="/Object">Object</a></div></div><div class="member-body"><p class="description">Returns a new <code>Array</code> containing the items returned by <code>iterator</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
var generator = function*() {
yield "foo";
yield* ["bar", "baz"];
};
console.log(Array.from(generator()));
// With a map function
var mapFunction = function(value) {
return value.toUpperCase();
};
console.log(Array.from(generator(), mapFunction));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.from"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.from" class="spec">Spec</a></div></div></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="isArray"></a> <a name="isArray_Object"></a><div class="declaration"><span class="membername primary">isArray</span>(<span class="membername">value</span> : <a class="membertype" href="/Object">Object</a>) : <a class="membertype" href="/Boolean">Boolean</a></div><div class="member-body"><p class="description">Returns <code>true</code> if <code>value</code> is an <code>Array</code>.</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
console.log(Array.isArray([]));
console.log(Array.isArray({}));
console.log(Array.isArray(53));
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.isArray"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><a href="http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.3.2" class="spec">Spec</a></div></div></div><div class="member"><div class="expand-members" title="Toggle showing all descriptions and examples"></div><a name="of"></a> <a name="of_Object_Object_dotdotdot"></a><div class="declaration"><span class="membername primary">of</span>(<span class="membername">item0</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">item1</span> : <a class="membertype" href="/Object">Object</a>, <span class="optional">[<span class="membername">...</span>]</span>]</span>) : <a class="membertype" href="/Array">Array</a></div><div class="member-body"><p class="description">Creates an <code>Array</code> with the specified parameters as the 0th, 1st, ... items of the <code>Array</code>. Can also be constructed as <code>[item0, item1, ...]</code>. Note that <code>Array.of(x)</code> will always create an array of length <code>1</code> containing <code>x</code>, while <a href="#new_Array_Number"><code>new Array(x)</code></a> will create an array of length <code>x</code> if <code>x</code> is an integer (and throw an exception if <code>x</code> is a non-integer <a href="/Number">Number</a>).</p><div class="example"><div class="codePanel"><h4>Example:</h4><textarea class="code" rows="12" cols="60" wrap="off">
// The following are equivalent
var w = ['a', 'b', 'c'];
var x = Array('a', 'b', 'c');
var y = new Array('a', 'b', 'c');
var z = Array.of('a', 'b', 'c');
</textarea><a onclick='executeExample(this.parentNode.parentNode, "Array.of"); return false' href="#" class="run">Run</a></div><div class="resultsPanel"><h4>Results:</h4><div style="position: relative"><div class="errormessage" style="display: none"></div><pre class="results"> </pre></div></div></div><p></p><div class="membermetadata"><span class="ecmascript2015">ECMAScript 2015</span> <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-array.of" class="spec">Spec</a></div></div></div></div><div class="bottomnav"><a href="/">home</a> <a href="/license">license</a> <a href="https://github.com/nkronlage/JavaScripture">contribute</a> <a href="/feedback">feedback</a> <a id="toggle-theme" href="#">toggle light/dark mode</a></div><div class="copyright">Copyright © JavaScripture Contributors</div></div></div></body><script src="javascripture.js"></script></html>