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37 lines
986 B
JavaScript
37 lines
986 B
JavaScript
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'use strict';
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// btoa polyfill for IE<10 courtesy https://github.com/davidchambers/Base64.js
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var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
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function E() {
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this.message = 'String contains an invalid character';
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}
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E.prototype = new Error;
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E.prototype.code = 5;
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E.prototype.name = 'InvalidCharacterError';
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function btoa(input) {
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var str = String(input);
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var output = '';
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for (
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// initialize result and counter
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var block, charCode, idx = 0, map = chars;
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// if the next str index does not exist:
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// change the mapping table to "="
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// check if d has no fractional digits
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str.charAt(idx | 0) || (map = '=', idx % 1);
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// "8 - idx % 1 * 8" generates the sequence 2, 4, 6, 8
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output += map.charAt(63 & block >> 8 - idx % 1 * 8)
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) {
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charCode = str.charCodeAt(idx += 3 / 4);
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if (charCode > 0xFF) {
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throw new E();
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}
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block = block << 8 | charCode;
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}
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return output;
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}
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module.exports = btoa;
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