esnext.uint8-array.to-base64.js 1.6 KB

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  1. 'use strict';
  2. var $ = require('../internals/export');
  3. var global = require('../internals/global');
  4. var uncurryThis = require('../internals/function-uncurry-this');
  5. var anObjectOrUndefined = require('../internals/an-object-or-undefined');
  6. var anUint8Array = require('../internals/an-uint8-array');
  7. var base64Map = require('../internals/base64-map');
  8. var getAlphabetOption = require('../internals/get-alphabet-option');
  9. var base64Alphabet = base64Map.i2c;
  10. var base64UrlAlphabet = base64Map.i2cUrl;
  11. var Uint8Array = global.Uint8Array;
  12. var charAt = uncurryThis(''.charAt);
  13. // `Uint8Array.prototype.toBase64` method
  14. // https://github.com/tc39/proposal-arraybuffer-base64
  15. if (Uint8Array) $({ target: 'Uint8Array', proto: true, forced: true }, {
  16. toBase64: function toBase64(/* options */) {
  17. var array = anUint8Array(this);
  18. var options = arguments.length ? anObjectOrUndefined(arguments[0]) : undefined;
  19. var alphabet = getAlphabetOption(options) === 'base64' ? base64Alphabet : base64UrlAlphabet;
  20. var result = '';
  21. var i = 0;
  22. var length = array.length;
  23. var triplet;
  24. var at = function (shift) {
  25. return charAt(alphabet, (triplet >> (6 * shift)) & 63);
  26. };
  27. for (; i + 2 < length; i += 3) {
  28. triplet = (array[i] << 16) + (array[i + 1] << 8) + array[i + 2];
  29. result += at(3) + at(2) + at(1) + at(0);
  30. }
  31. if (i + 2 === length) {
  32. triplet = (array[i] << 16) + (array[i + 1] << 8);
  33. result += at(3) + at(2) + at(1) + '=';
  34. } else if (i + 1 === length) {
  35. triplet = array[i] << 16;
  36. result += at(3) + at(2) + '==';
  37. }
  38. return result;
  39. }
  40. });