29 lines
1.4 KiB
JavaScript
29 lines
1.4 KiB
JavaScript
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'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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