es.array-buffer.slice.js 1.6 KB

123456789101112131415161718192021222324252627282930313233343536373839
  1. 'use strict';
  2. var $ = require('../internals/export');
  3. var uncurryThis = require('../internals/function-uncurry-this-clause');
  4. var fails = require('../internals/fails');
  5. var ArrayBufferModule = require('../internals/array-buffer');
  6. var anObject = require('../internals/an-object');
  7. var toAbsoluteIndex = require('../internals/to-absolute-index');
  8. var toLength = require('../internals/to-length');
  9. var ArrayBuffer = ArrayBufferModule.ArrayBuffer;
  10. var DataView = ArrayBufferModule.DataView;
  11. var DataViewPrototype = DataView.prototype;
  12. var nativeArrayBufferSlice = uncurryThis(ArrayBuffer.prototype.slice);
  13. var getUint8 = uncurryThis(DataViewPrototype.getUint8);
  14. var setUint8 = uncurryThis(DataViewPrototype.setUint8);
  15. var INCORRECT_SLICE = fails(function () {
  16. return !new ArrayBuffer(2).slice(1, undefined).byteLength;
  17. });
  18. // `ArrayBuffer.prototype.slice` method
  19. // https://tc39.es/ecma262/#sec-arraybuffer.prototype.slice
  20. $({ target: 'ArrayBuffer', proto: true, unsafe: true, forced: INCORRECT_SLICE }, {
  21. slice: function slice(start, end) {
  22. if (nativeArrayBufferSlice && end === undefined) {
  23. return nativeArrayBufferSlice(anObject(this), start); // FF fix
  24. }
  25. var length = anObject(this).byteLength;
  26. var first = toAbsoluteIndex(start, length);
  27. var fin = toAbsoluteIndex(end === undefined ? length : end, length);
  28. var result = new ArrayBuffer(toLength(fin - first));
  29. var viewSource = new DataView(this);
  30. var viewTarget = new DataView(result);
  31. var index = 0;
  32. while (first < fin) {
  33. setUint8(viewTarget, index++, getUint8(viewSource, first++));
  34. } return result;
  35. }
  36. });