| 1 | 'use strict';
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| 2 | var toObject = require('../internals/to-object');
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| 3 | var toAbsoluteIndex = require('../internals/to-absolute-index');
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| 4 | var toLength = require('../internals/to-length');
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| 5 |
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| 6 | var min = Math.min;
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| 7 |
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| 8 |
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| 9 |
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| 10 | module.exports = [].copyWithin || function copyWithin(target /* = 0 */, start /* = 0, end = @length */) {
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| 11 | var O = toObject(this);
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| 12 | var len = toLength(O.length);
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| 13 | var to = toAbsoluteIndex(target, len);
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| 14 | var from = toAbsoluteIndex(start, len);
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| 15 | var end = arguments.length > 2 ? arguments[2] : undefined;
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| 16 | var count = min((end === undefined ? len : toAbsoluteIndex(end, len)) - from, len - to);
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| 17 | var inc = 1;
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| 18 | if (from < to && to < from + count) {
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| 19 | inc = -1;
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| 20 | from += count - 1;
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| 21 | to += count - 1;
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| 22 | }
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| 23 | while (count-- > 0) {
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| 24 | if (from in O) O[to] = O[from];
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| 25 | else delete O[to];
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| 26 | to += inc;
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| 27 | from += inc;
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| 28 | } return O;
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| 29 | };
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