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- 'use strict';
- var toObject = require('../internals/to-object');
- var toAbsoluteIndex = require('../internals/to-absolute-index');
- var lengthOfArrayLike = require('../internals/length-of-array-like');
- var deletePropertyOrThrow = require('../internals/delete-property-or-throw');
- var min = Math.min;
- // `Array.prototype.copyWithin` method implementation
- // https://tc39.es/ecma262/#sec-array.prototype.copywithin
- // eslint-disable-next-line es/no-array-prototype-copywithin -- safe
- module.exports = [].copyWithin || function copyWithin(target /* = 0 */, start /* = 0, end = @length */) {
- var O = toObject(this);
- var len = lengthOfArrayLike(O);
- var to = toAbsoluteIndex(target, len);
- var from = toAbsoluteIndex(start, len);
- var end = arguments.length > 2 ? arguments[2] : undefined;
- var count = min((end === undefined ? len : toAbsoluteIndex(end, len)) - from, len - to);
- var inc = 1;
- if (from < to && to < from + count) {
- inc = -1;
- from += count - 1;
- to += count - 1;
- }
- while (count-- > 0) {
- if (from in O) O[to] = O[from];
- else deletePropertyOrThrow(O, to);
- to += inc;
- from += inc;
- } return O;
- };
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