-
Notifications
You must be signed in to change notification settings - Fork 13
Expand file tree
/
Copy pathasync-iterators.html
More file actions
67 lines (63 loc) · 24.1 KB
/
async-iterators.html
File metadata and controls
67 lines (63 loc) · 24.1 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
<!DOCTYPE html>
<html lang="en-US">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>JavsScript - Async Iterators</title>
<meta name="generator" content="VuePress 1.8.2">
<link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png">
<link rel="icon" type="image/png" sizes="16x16" href="/favicon-16x16.png">
<link rel="manifest" href="/site.webmanifest">
<link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png">
<link rel="mask-icon" href="/safari-pinned-tab.svg" color="#5bbad5">
<meta name="description" content="Basics">
<meta property="og:site_name" content="DevTut">
<meta property="og:title" content="JavsScript - Async Iterators">
<meta property="og:description" content="Basics">
<meta property="og:type" content="article">
<meta property="og:url" content="/javascript/async-iterators.html">
<meta property="og:image" content="/logo.png">
<meta name="twitter:title" content="JavsScript - Async Iterators">
<meta name="twitter:description" content="Basics">
<meta name="twitter:url" content="/javascript/async-iterators.html">
<meta name="twitter:card" content="summary_large_image">
<meta name="twitter:image" content="/logo.png">
<meta name="theme-color" content="#ffffff">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<meta name="msapplication-TileImage" content="/mstile-150x150.png">
<meta name="msapplication-TileColor" content="#da532c">
<meta name="google-site-verification" content="76_rKXgwMVIjd-axJC_1zPV9OS4mEjvtgjYOWVkAdnQ">
<link rel="preload" href="/assets/css/0.styles.60619e34.css" as="style"><link rel="preload" href="/assets/js/app.1779e102.js" as="script"><link rel="preload" href="/assets/js/3.2cfa8016.js" as="script"><link rel="preload" href="/assets/js/1705.6347dfdd.js" as="script">
<link rel="stylesheet" href="/assets/css/0.styles.60619e34.css">
</head>
<body>
<div id="app" data-server-rendered="true"><div class="theme-container"><header class="navbar"><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <a href="/" class="home-link router-link-active"><!----> <span class="site-name">DevTut</span></a> <div class="links"><form id="search-form" role="search" class="algolia-search-wrapper search-box"><input id="algolia-search-input" class="search-query"></form> <nav class="nav-links can-hide"> <a href="https://github.com/devtut/generate" target="_blank" rel="noopener noreferrer" class="repo-link">
GitHub
<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></nav></div></header> <div class="sidebar-mask"></div> <aside class="sidebar"><nav class="nav-links"> <a href="https://github.com/devtut/generate" target="_blank" rel="noopener noreferrer" class="repo-link">
GitHub
<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></nav> <ul class="sidebar-links"><li><section class="sidebar-group depth-0"><p class="sidebar-heading open"><span>JavaScript</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/javascript/" aria-current="page" class="sidebar-link">Disclaimer</a></li><li><a href="/javascript/getting-started-with-javascript.html" class="sidebar-link">Getting started with JavaScript</a></li><li><a href="/javascript/javascript-variables.html" class="sidebar-link">JavaScript Variables</a></li><li><a href="/javascript/built-in-constants.html" class="sidebar-link">Built-in Constants</a></li><li><a href="/javascript/comments.html" class="sidebar-link">Comments</a></li><li><a href="/javascript/console.html" class="sidebar-link">Console</a></li><li><a href="/javascript/datatypes-in-javascript.html" class="sidebar-link">Datatypes in Javascript</a></li><li><a href="/javascript/strings.html" class="sidebar-link">Strings</a></li><li><a href="/javascript/date.html" class="sidebar-link">Date</a></li><li><a href="/javascript/date-comparison.html" class="sidebar-link">Date Comparison</a></li><li><a href="/javascript/comparison-operations.html" class="sidebar-link">Comparison Operations</a></li><li><a href="/javascript/conditions.html" class="sidebar-link">Conditions</a></li><li><a href="/javascript/arrays.html" class="sidebar-link">Arrays</a></li><li><a href="/javascript/objects.html" class="sidebar-link">Objects</a></li><li><a href="/javascript/arithmetic-math.html" class="sidebar-link">Arithmetic (Math)</a></li><li><a href="/javascript/bitwise-operators.html" class="sidebar-link">Bitwise operators</a></li><li><a href="/javascript/constructor-functions.html" class="sidebar-link">Constructor functions</a></li><li><a href="/javascript/declarations-and-assignments.html" class="sidebar-link">Declarations and Assignments</a></li><li><a href="/javascript/loops.html" class="sidebar-link">Loops</a></li><li><a href="/javascript/functions.html" class="sidebar-link">Functions</a></li><li><a href="/javascript/functional-javascript.html" class="sidebar-link">Functional JavaScript</a></li><li><a href="/javascript/prototypes-objects.html" class="sidebar-link">Prototypes, objects</a></li><li><a href="/javascript/classes.html" class="sidebar-link">Classes</a></li><li><a href="/javascript/namespacing.html" class="sidebar-link">Namespacing</a></li><li><a href="/javascript/context-this.html" class="sidebar-link">Context (this)</a></li><li><a href="/javascript/setters-and-getters.html" class="sidebar-link">Setters and Getters</a></li><li><a href="/javascript/events.html" class="sidebar-link">Events</a></li><li><a href="/javascript/inheritance.html" class="sidebar-link">Inheritance</a></li><li><a href="/javascript/method-chaining.html" class="sidebar-link">Method Chaining</a></li><li><a href="/javascript/callbacks.html" class="sidebar-link">Callbacks</a></li><li><a href="/javascript/intervals-and-timeouts.html" class="sidebar-link">Intervals and Timeouts</a></li><li><a href="/javascript/regular-expressions.html" class="sidebar-link">Regular expressions</a></li><li><a href="/javascript/cookies.html" class="sidebar-link">Cookies</a></li><li><a href="/javascript/web-storage.html" class="sidebar-link">Web Storage</a></li><li><a href="/javascript/data-attributes.html" class="sidebar-link">Data attributes</a></li><li><a href="/javascript/json.html" class="sidebar-link">JSON</a></li><li><a href="/javascript/ajax.html" class="sidebar-link">AJAX</a></li><li><a href="/javascript/enumerations.html" class="sidebar-link">Enumerations</a></li><li><a href="/javascript/map.html" class="sidebar-link">Map</a></li><li><a href="/javascript/timestamps.html" class="sidebar-link">Timestamps</a></li><li><a href="/javascript/unary-operators.html" class="sidebar-link">Unary Operators</a></li><li><a href="/javascript/generators.html" class="sidebar-link">Generators</a></li><li><a href="/javascript/promises.html" class="sidebar-link">Promises</a></li><li><a href="/javascript/set.html" class="sidebar-link">Set</a></li><li><a href="/javascript/modals-prompts.html" class="sidebar-link">Modals - Prompts</a></li><li><a href="/javascript/execcommand-and-contenteditable.html" class="sidebar-link">execCommand and contenteditable</a></li><li><a href="/javascript/history.html" class="sidebar-link">History</a></li><li><a href="/javascript/navigator-object.html" class="sidebar-link">Navigator Object</a></li><li><a href="/javascript/bom-browser-object-model.html" class="sidebar-link">BOM (Browser Object Model)</a></li><li><a href="/javascript/the-event-loop.html" class="sidebar-link">The Event Loop</a></li><li><a href="/javascript/strict-mode.html" class="sidebar-link">Strict mode</a></li><li><a href="/javascript/custom-elements.html" class="sidebar-link">Custom Elements</a></li><li><a href="/javascript/data-manipulation.html" class="sidebar-link">Data Manipulation</a></li><li><a href="/javascript/binary-data.html" class="sidebar-link">Binary Data</a></li><li><a href="/javascript/template-literals.html" class="sidebar-link">Template Literals</a></li><li><a href="/javascript/fetch.html" class="sidebar-link">Fetch</a></li><li><a href="/javascript/scope.html" class="sidebar-link">Scope</a></li><li><a href="/javascript/modules.html" class="sidebar-link">Modules</a></li><li><a href="/javascript/screen.html" class="sidebar-link">Screen</a></li><li><a href="/javascript/variable-coercion-conversion.html" class="sidebar-link">Variable coercion/conversion</a></li><li><a href="/javascript/destructuring-assignment.html" class="sidebar-link">Destructuring assignment</a></li><li><a href="/javascript/websockets.html" class="sidebar-link">WebSockets</a></li><li><a href="/javascript/arrow-functions.html" class="sidebar-link">Arrow Functions</a></li><li><a href="/javascript/workers.html" class="sidebar-link">Workers</a></li><li><a href="/javascript/requestanimationframe.html" class="sidebar-link">requestAnimationFrame</a></li><li><a href="/javascript/creational-design-patterns.html" class="sidebar-link">Creational Design Patterns</a></li><li><a href="/javascript/detecting-browser.html" class="sidebar-link">Detecting browser</a></li><li><a href="/javascript/symbols.html" class="sidebar-link">Symbols</a></li><li><a href="/javascript/transpiling.html" class="sidebar-link">Transpiling</a></li><li><a href="/javascript/automatic-semicolon-insertion-asi.html" class="sidebar-link">Automatic Semicolon Insertion - ASI</a></li><li><a href="/javascript/localization.html" class="sidebar-link">Localization</a></li><li><a href="/javascript/geolocation.html" class="sidebar-link">Geolocation</a></li><li><a href="/javascript/indexeddb.html" class="sidebar-link">IndexedDB</a></li><li><a href="/javascript/modularization-techniques.html" class="sidebar-link">Modularization Techniques</a></li><li><a href="/javascript/proxy.html" class="sidebar-link">Proxy</a></li><li><a href="/javascript/postmessage-and-messageevent.html" class="sidebar-link">.postMessage() and MessageEvent</a></li><li><a href="/javascript/weakmap.html" class="sidebar-link">WeakMap</a></li><li><a href="/javascript/weakset.html" class="sidebar-link">WeakSet</a></li><li><a href="/javascript/escape-sequences.html" class="sidebar-link">Escape Sequences</a></li><li><a href="/javascript/behavioral-design-patterns.html" class="sidebar-link">Behavioral Design Patterns</a></li><li><a href="/javascript/server-sent-events.html" class="sidebar-link">Server-sent events</a></li><li><a href="/javascript/async-functions-async-await.html" class="sidebar-link">Async functions (async/await)</a></li><li><a href="/javascript/async-iterators.html" aria-current="page" class="active sidebar-link">Async Iterators</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/javascript/async-iterators.html#basics" class="sidebar-link">Basics</a></li></ul></li><li><a href="/javascript/how-to-make-iterator-usable-inside-async-callback-function.html" class="sidebar-link">How to make iterator usable inside async callback function</a></li><li><a href="/javascript/tail-call-optimization.html" class="sidebar-link">Tail Call Optimization</a></li><li><a href="/javascript/bitwise-operators-real-world-examples-snippets.html" class="sidebar-link">Bitwise Operators - Real World Examples (snippets)</a></li><li><a href="/javascript/tilde.html" class="sidebar-link">Tilde ~</a></li><li><a href="/javascript/using-javascript-to-get-set-css-custom-variables.html" class="sidebar-link">Using javascript to get/set CSS custom variables</a></li><li><a href="/javascript/selection-api.html" class="sidebar-link">Selection API</a></li><li><a href="/javascript/file-api-blobs-and-filereaders.html" class="sidebar-link">File API, Blobs and FileReaders</a></li><li><a href="/javascript/notifications-api.html" class="sidebar-link">Notifications API</a></li><li><a href="/javascript/vibration-api.html" class="sidebar-link">Vibration API</a></li><li><a href="/javascript/battery-status-api.html" class="sidebar-link">Battery Status API</a></li><li><a href="/javascript/fluent-api.html" class="sidebar-link">Fluent API</a></li><li><a href="/javascript/web-cryptography-api.html" class="sidebar-link">Web Cryptography API</a></li><li><a href="/javascript/security-issues.html" class="sidebar-link">Security issues</a></li><li><a href="/javascript/same-origin-policy-cross-origin-communication.html" class="sidebar-link">Same Origin Policy & Cross-Origin Communication</a></li><li><a href="/javascript/error-handling.html" class="sidebar-link">Error Handling</a></li><li><a href="/javascript/global-error-handling-in-browsers.html" class="sidebar-link">Global error handling in browsers</a></li><li><a href="/javascript/debugging.html" class="sidebar-link">Debugging</a></li><li><a href="/javascript/unit-testing-javascript.html" class="sidebar-link">Unit Testing Javascript</a></li><li><a href="/javascript/evaluating-javascript.html" class="sidebar-link">Evaluating JavaScript</a></li><li><a href="/javascript/linters-ensuring-code-quality.html" class="sidebar-link">Linters - Ensuring code quality</a></li><li><a href="/javascript/anti-patterns.html" class="sidebar-link">Anti-patterns</a></li><li><a href="/javascript/performance-tips.html" class="sidebar-link">Performance Tips</a></li><li><a href="/javascript/memory-efficiency.html" class="sidebar-link">Memory efficiency</a></li><li><a href="/javascript/reserved-keywords.html" class="sidebar-link">Reserved Keywords</a></li><li><a href="/javascript/contributors.html" class="sidebar-link">The Contributors</a></li></ul></section></li></ul> </aside> <main class="page"> <div class="theme-default-content content__default"><h1 id="async-iterators"><a href="#async-iterators" class="header-anchor">#</a> Async Iterators</h1> <p>An <code>async</code> function is one that returns a promise. <code>await</code> yields to the caller until the promise resolves and then continues with the result.</p> <p>An iterator allows the collection to be looped through with a <code>for-of</code> loop.</p> <p>An async iterator is a collection where each iteration is a promise which can be awaited using a <code>for-await-of</code> loop.</p> <p>Async iterators are a <a href="https://github.com/tc39/proposal-async-iteration" target="_blank" rel="noopener noreferrer">stage 3 proposal<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a>. They are in Chrome Canary 60 with <code>--harmony-async-iteration</code></p> <h2 id="basics"><a href="#basics" class="header-anchor">#</a> Basics</h2> <p>A JavaScript <code>Iterator</code> is an object with a <code>.next()</code> method, which returns an <code>IteratorItem</code>, which is an object with <code>value : <any></code> and <code>done : <boolean></code>.</p> <p>A JavaScript <code>AsyncIterator</code> is an object with a <code>.next()</code> method, which returns a <code>Promise<IteratorItem></code>, a <strong>promise</strong> for the next value.</p> <p>To create an AsyncIterator, we can use the <strong>async generator</strong> syntax:</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token comment">/**
* Returns a promise which resolves after time had passed.
*/</span>
<span class="token keyword">const</span> <span class="token function-variable function">delay</span> <span class="token operator">=</span> <span class="token parameter">time</span> <span class="token operator">=></span> <span class="token keyword">new</span> <span class="token class-name">Promise</span><span class="token punctuation">(</span><span class="token parameter">resolve</span> <span class="token operator">=></span> <span class="token function">setTimeout</span><span class="token punctuation">(</span>resolve<span class="token punctuation">,</span> time<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">async</span> <span class="token keyword">function</span><span class="token operator">*</span> <span class="token function">delayedRange</span><span class="token punctuation">(</span><span class="token parameter">max</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> max<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">await</span> <span class="token function">delay</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">yield</span> i<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre></div><p>The <code>delayedRange</code> function will take a maximum number, and returns an <code>AsyncIterator</code>, which yields numbers from 0 to that number, in 1 second intervals.</p> <p>Usage:</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">for</span> <span class="token keyword">await</span> <span class="token punctuation">(</span><span class="token keyword">let</span> number <span class="token keyword">of</span> <span class="token function">delayedRange</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>number<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre></div><p>The <code>for await of</code> loop is another piece of new syntax, available only inside of async functions, as well as async generators. Inside the loop, the values yielded (which, remember, are Promises) are unwrapped, so the Promise is hidden away. Within the loop, you can deal with the direct values (the yielded numbers), the <code>for await of</code> loop will wait for the Promises on your behalf.</p> <p>The above example will wait 1 second, log 0, wait another second, log 1, and so on, until it logs 9. At which point the <code>AsyncIterator</code> will be <code>done</code>, and the <code>for await of</code> loop will exit.</p> <h4 id="syntax"><a href="#syntax" class="header-anchor">#</a> Syntax</h4> <ul><li>async function* asyncGenerator() {}</li> <li>yield await asyncOperationWhichReturnsAPromise();</li> <li>for await (let result of asyncGenerator()) { /* result is the resolved value from the promise */ }</li></ul> <h4 id="remarks"><a href="#remarks" class="header-anchor">#</a> Remarks</h4> <p>An async iterator is a <strong>declarative pull stream</strong> as opposed to an Observable's declarative <strong>push</strong> stream.</p> <h3 id="useful-links"><a href="#useful-links" class="header-anchor">#</a> Useful Links</h3> <ul><li><a href="https://github.com/tc39/proposal-async-iteration" target="_blank" rel="noopener noreferrer">Async Iteration spec proposal<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li> <li><a href="https://jakearchibald.com/2017/async-iterators-and-generators/" target="_blank" rel="noopener noreferrer">Introduction to their use<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li> <li><a href="https://github.com/KeithHenry/event-generator" target="_blank" rel="noopener noreferrer">Event subscription proof of concept<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></li></ul></div> <footer class="page-edit"><div class="edit-link"><a href="https://github.com/devtut/generate/edit/master/docs/javascript/async-iterators.md" target="_blank" rel="noopener noreferrer">Edit this page on GitHub</a> <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></div> <!----></footer> <div class="page-nav"><p class="inner"><span class="prev">
←
<a href="/javascript/async-functions-async-await.html" class="prev">
Async functions (async/await)
</a></span> <span class="next"><a href="/javascript/how-to-make-iterator-usable-inside-async-callback-function.html">
How to make iterator usable inside async callback function
</a>
→
</span></p></div> </main></div><div class="global-ui"><!----></div></div>
<script src="/assets/js/app.1779e102.js" defer></script><script src="/assets/js/3.2cfa8016.js" defer></script><script src="/assets/js/1705.6347dfdd.js" defer></script>
</body>
</html>