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28 lines
1.4 KiB
28 lines
1.4 KiB
'use strict'; |
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var toIndexedObject = require('../internals/to-indexed-object'); |
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var toInteger = require('../internals/to-integer'); |
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var toLength = require('../internals/to-length'); |
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var arrayMethodIsStrict = require('../internals/array-method-is-strict'); |
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var arrayMethodUsesToLength = require('../internals/array-method-uses-to-length'); |
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var min = Math.min; |
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var nativeLastIndexOf = [].lastIndexOf; |
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var NEGATIVE_ZERO = !!nativeLastIndexOf && 1 / [1].lastIndexOf(1, -0) < 0; |
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var STRICT_METHOD = arrayMethodIsStrict('lastIndexOf'); |
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// For preventing possible almost infinite loop in non-standard implementations, test the forward version of the method |
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var USES_TO_LENGTH = arrayMethodUsesToLength('indexOf', { ACCESSORS: true, 1: 0 }); |
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var FORCED = NEGATIVE_ZERO || !STRICT_METHOD || !USES_TO_LENGTH; |
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// `Array.prototype.lastIndexOf` method implementation |
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// https://tc39.github.io/ecma262/#sec-array.prototype.lastindexof |
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module.exports = FORCED ? function lastIndexOf(searchElement /* , fromIndex = @[*-1] */) { |
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// convert -0 to +0 |
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if (NEGATIVE_ZERO) return nativeLastIndexOf.apply(this, arguments) || 0; |
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var O = toIndexedObject(this); |
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var length = toLength(O.length); |
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var index = length - 1; |
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if (arguments.length > 1) index = min(index, toInteger(arguments[1])); |
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if (index < 0) index = length + index; |
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for (;index >= 0; index--) if (index in O && O[index] === searchElement) return index || 0; |
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return -1; |
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} : nativeLastIndexOf;
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