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29 lines
969 B
29 lines
969 B
'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 toLength = require('../internals/to-length'); |
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var min = Math.min; |
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// `Array.prototype.copyWithin` method implementation |
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// https://tc39.github.io/ecma262/#sec-array.prototype.copywithin |
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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 = toLength(O.length); |
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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 delete 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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