ArrayBufferByteLength.js 1.6 KB

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  1. 'use strict';
  2. var $TypeError = require('es-errors/type');
  3. // https://tc39.es/ecma262/#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 isGrowable = false; // TODO: support this
  9. module.exports = function ArrayBufferByteLength(arrayBuffer, order) {
  10. var isSAB = isSharedArrayBuffer(arrayBuffer);
  11. if (!isArrayBuffer(arrayBuffer) && !isSAB) {
  12. throw new $TypeError('Assertion failed: `arrayBuffer` must be an ArrayBuffer or a SharedArrayBuffer');
  13. }
  14. if (order !== 'SEQ-CST' && order !== 'UNORDERED') {
  15. throw new $TypeError('Assertion failed: `order` must be ~SEQ-CST~ or ~UNORDERED~');
  16. }
  17. // 1. If IsSharedArrayBuffer(arrayBuffer) is true and arrayBuffer has an [[ArrayBufferByteLengthData]] internal slot, then
  18. // TODO: see if IsFixedLengthArrayBuffer can be used here in the spec instead
  19. if (isSAB && isGrowable) { // step 1
  20. // a. Let bufferByteLengthBlock be arrayBuffer.[[ArrayBufferByteLengthData]].
  21. // b. Let rawLength be GetRawBytesFromSharedBlock(bufferByteLengthBlock, 0, BIGUINT64, true, order).
  22. // c. Let isLittleEndian be the value of the [[LittleEndian]] field of the surrounding agent's Agent Record.
  23. // d. Return ℝ(RawBytesToNumeric(BIGUINT64, rawLength, isLittleEndian)).
  24. }
  25. if (IsDetachedBuffer(arrayBuffer)) {
  26. throw new $TypeError('Assertion failed: `arrayBuffer` must not be detached'); // step 2
  27. }
  28. return arrayBufferByteLength(arrayBuffer);
  29. };