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- // 22.1.3.3 Array.prototype.copyWithin(target, start, end = this.length)
- 'use strict';
- var toObject = require('./_to-object');
- var toAbsoluteIndex = require('./_to-absolute-index');
- var toLength = require('./_to-length');
- module.exports = [].copyWithin || function copyWithin(target /* = 0 */, start /* = 0, end = @length */) {
- var O = toObject(this);
- var len = toLength(O.length);
- var to = toAbsoluteIndex(target, len);
- var from = toAbsoluteIndex(start, len);
- var end = arguments.length > 2 ? arguments[2] : undefined;
- var count = Math.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 delete O[to];
- to += inc;
- from += inc;
- } return O;
- };
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