ArrayBufferByteLength.js 1.7 KB

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  1. 'use strict';
  2. var $TypeError = require('es-errors/type');
  3. // https://262.ecma-international.org/15.0/#sec-arraybufferbytelength
  4. var IsDetachedBuffer = require('./IsDetachedBuffer');
  5. var isArrayBuffer = require('is-array-buffer');
  6. var isSharedArrayBuffer = require('is-shared-array-buffer');
  7. var arrayBufferByteLength = require('array-buffer-byte-length');
  8. var callBound = require('call-bound');
  9. var $sabByteLength = callBound('SharedArrayBuffer.prototype.byteLength', true);
  10. var isGrowable = false; // TODO: support this
  11. module.exports = function ArrayBufferByteLength(arrayBuffer, order) {
  12. var isSAB = isSharedArrayBuffer(arrayBuffer);
  13. if (!isArrayBuffer(arrayBuffer) && !isSAB) {
  14. throw new $TypeError('Assertion failed: `arrayBuffer` must be an ArrayBuffer or a SharedArrayBuffer');
  15. }
  16. if (order !== 'SEQ-CST' && order !== 'UNORDERED') {
  17. throw new $TypeError('Assertion failed: `order` must be ~SEQ-CST~ or ~UNORDERED~');
  18. }
  19. // 1. If IsSharedArrayBuffer(arrayBuffer) is true and arrayBuffer has an [[ArrayBufferByteLengthData]] internal slot, then
  20. // TODO: see if IsFixedLengthArrayBuffer can be used here in the spec instead
  21. if (isSAB && isGrowable) { // step 1
  22. // a. Let bufferByteLengthBlock be arrayBuffer.[[ArrayBufferByteLengthData]].
  23. // b. Let rawLength be GetRawBytesFromSharedBlock(bufferByteLengthBlock, 0, BIGUINT64, true, order).
  24. // c. Let isLittleEndian be the value of the [[LittleEndian]] field of the surrounding agent's Agent Record.
  25. // d. Return ℝ(RawBytesToNumeric(BIGUINT64, rawLength, isLittleEndian)).
  26. }
  27. if (IsDetachedBuffer(arrayBuffer)) {
  28. throw new $TypeError('Assertion failed: `arrayBuffer` must not be detached'); // step 2
  29. }
  30. return isSAB ? $sabByteLength(arrayBuffer) : arrayBufferByteLength(arrayBuffer);
  31. };