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