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39 lines
1.1 KiB
39 lines
1.1 KiB
'use strict'; |
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var GetIntrinsic = require('get-intrinsic'); |
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var callBound = require('call-bind/callBound'); |
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var $TypeError = GetIntrinsic('%TypeError%'); |
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var IsIntegralNumber = require('./IsIntegralNumber'); |
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var Type = require('./Type'); |
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var $slice = callBound('String.prototype.slice'); |
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// https://ecma-international.org/ecma-262/12.0/#sec-stringindexof |
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module.exports = function StringIndexOf(string, searchValue, fromIndex) { |
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if (Type(string) !== 'String') { |
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throw new $TypeError('Assertion failed: `string` must be a String'); |
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} |
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if (Type(searchValue) !== 'String') { |
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throw new $TypeError('Assertion failed: `searchValue` must be a String'); |
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} |
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if (!IsIntegralNumber(fromIndex) || fromIndex < 0) { |
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throw new $TypeError('Assertion failed: `fromIndex` must be a non-negative integer'); |
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} |
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var len = string.length; |
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if (searchValue === '' && fromIndex <= len) { |
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return fromIndex; |
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} |
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var searchLen = searchValue.length; |
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for (var i = fromIndex; i <= (len - searchLen); i += 1) { |
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var candidate = $slice(string, i, i + searchLen); |
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if (candidate === searchValue) { |
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return i; |
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} |
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} |
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return -1; |
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};
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