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ToIndex.js 679B

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  1. 'use strict';
  2. var GetIntrinsic = require('../GetIntrinsic');
  3. var $RangeError = GetIntrinsic('%RangeError%');
  4. var ToInteger = require('./ToInteger');
  5. var ToLength = require('./ToLength');
  6. var SameValueZero = require('./SameValueZero');
  7. // https://www.ecma-international.org/ecma-262/8.0/#sec-toindex
  8. module.exports = function ToIndex(value) {
  9. if (typeof value === 'undefined') {
  10. return 0;
  11. }
  12. var integerIndex = ToInteger(value);
  13. if (integerIndex < 0) {
  14. throw new $RangeError('index must be >= 0');
  15. }
  16. var index = ToLength(integerIndex);
  17. if (!SameValueZero(integerIndex, index)) {
  18. throw new $RangeError('index must be >= 0 and < 2 ** 53 - 1');
  19. }
  20. return index;
  21. };