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base64Utils.js
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79 lines (69 loc) · 2.41 KB
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// Copied from https://github.com/strophe/strophejs/blob/e06d027/src/polyfills.js#L149
// This code was written by Tyler Akins and has been placed in the
// public domain. It would be nice if you left this header intact.
// Base64 code from Tyler Akins -- http://rumkin.com
/**
* Decodes a base64 string.
* @param {string} input The string to decode.
*/
var decodeBase64 = typeof atob === 'function' ? atob : function (input) {
var keyStr = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
var output = '';
var chr1, chr2, chr3;
var enc1, enc2, enc3, enc4;
var i = 0;
// remove all characters that are not A-Z, a-z, 0-9, +, /, or =
input = input.replace(/[^A-Za-z0-9\+\/\=]/g, '');
do {
enc1 = keyStr.indexOf(input.charAt(i++));
enc2 = keyStr.indexOf(input.charAt(i++));
enc3 = keyStr.indexOf(input.charAt(i++));
enc4 = 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);
}
} while (i < input.length);
return output;
};
// Converts a string of base64 into a byte array.
// Throws error on invalid input.
function intArrayFromBase64(s) {
#if ENVIRONMENT_MAY_BE_NODE
if (typeof ENVIRONMENT_IS_NODE === 'boolean' && ENVIRONMENT_IS_NODE) {
var buf;
try {
// TODO: Update Node.js externs, Closure does not recognize the following Buffer.from()
/**@suppress{checkTypes}*/
buf = Buffer.from(s, 'base64');
} catch (_) {
buf = new Buffer(s, 'base64');
}
return new Uint8Array(buf['buffer'], buf['byteOffset'], buf['byteLength']);
}
#endif
try {
var decoded = decodeBase64(s);
var bytes = new Uint8Array(decoded.length);
for (var i = 0 ; i < decoded.length ; ++i) {
bytes[i] = decoded.charCodeAt(i);
}
return bytes;
} catch (_) {
throw new Error('Converting base64 string to bytes failed.');
}
}
// If filename is a base64 data URI, parses and returns data (Buffer on node,
// Uint8Array otherwise). If filename is not a base64 data URI, returns undefined.
function tryParseAsDataURI(filename) {
if (!isDataURI(filename)) {
return;
}
return intArrayFromBase64(filename.slice(dataURIPrefix.length));
}