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