// *Mainly, there are two ways to encode strings in JS* //

// -----------------Using btoa()------------------------//

// defining the string

const str = "Hello World";

// encoding the string

const result = window.btoa(str);

console.log(result);

// decoding the string

const result1 = window.atob(result);

console.log(result1);

// -----------------Using Base64 Object-------------------//-

// create Base64 Object

const Base64 = {

// private property

_keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

// public method for encoding

encode : function (input) {

let output = "";

let chr1, chr2, chr3, enc1, enc2, enc3, enc4;

let i = 0;

input = Base64._utf8_encode(input);

while (i < input.length) {

chr1 = input.charCodeAt(i++);

chr2 = input.charCodeAt(i++);

chr3 = input.charCodeAt(i++);

enc1 = chr1 >> 2;

enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);

enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);

enc4 = chr3 & 63;

if (isNaN(chr2)) {

enc3 = enc4 = 64;

} else if (isNaN(chr3)) {

enc4 = 64;

}

output = output +

Base64._keyStr.charAt(enc1) + Base64._keyStr.charAt(enc2) +

Base64._keyStr.charAt(enc3) + Base64._keyStr.charAt(enc4);

}

return output;

},

// public method for decoding

decode : function (input) {

let output = "";

let chr1, chr2, chr3;

let enc1, enc2, enc3, enc4;

let i = 0;

input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

while (i < input.length) {

enc1 = Base64._keyStr.indexOf(input.charAt(i++));

enc2 = Base64._keyStr.indexOf(input.charAt(i++));

enc3 = Base64._keyStr.indexOf(input.charAt(i++));

enc4 = Base64._keyStr.indexOf(input.charAt(i++));

chr1 = (enc1 << 2) | (enc2 >> 4);

chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);

chr3 = ((enc3 & 3) << 6) | enc4;

output = output + String.fromCharCode(chr1);

if (enc3 != 64) {

output = output + String.fromCharCode(chr2);

}

if (enc4 != 64) {

output = output + String.fromCharCode(chr3);

}

}

output = Base64._utf8_decode(output);

return output;

},

// private method for UTF-8 encoding

_utf8_encode : function (string) {

string = string.replace(/\r\n/g,"\n");

let utftext = "";

for (let n = 0; n < string.length; n++) {

let c = string.charCodeAt(n);

if (c < 128) {

utftext += String.fromCharCode(c);

}

else if((c > 127) && (c < 2048)) {

utftext += String.fromCharCode((c >> 6) | 192);

utftext += String.fromCharCode((c & 63) | 128);

}

else {

utftext += String.fromCharCode((c >> 12) | 224);

utftext += String.fromCharCode(((c >> 6) & 63) | 128);

utftext += String.fromCharCode((c & 63) | 128);

}

}

return utftext;

},

// private method for UTF-8 decoding

_utf8_decode : function (utftext) {

let string = "";

let i = 0;

let c = c1 = c2 = 0;

while ( i < utftext.length ) {

c = utftext.charCodeAt(i);

if (c < 128) {

string += String.fromCharCode(c);

i++;

}

else if((c > 191) && (c < 224)) {

c2 = utftext.charCodeAt(i+1);

string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));

i += 2;

}

else {

c2 = utftext.charCodeAt(i+1);

c3 = utftext.charCodeAt(i+2);

string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));

i += 3;

}

}

return string;

}

}

// define the string

const string = 'Learning JavaScript';

// encode the String

const encodedString = Base64.encode(string);

console.log(encodedString);

// decode the String

const decodedString = Base64.decode(encodedString);

console.log(decodedString);