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30 lines
858 B
30 lines
858 B
'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 StringToCodePoints = require('./StringToCodePoints'); |
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var Type = require('./Type'); |
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var $indexOf = callBound('String.prototype.indexOf'); |
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// https://ecma-international.org/ecma-262/13.0/#sec-getstringindex |
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module.exports = function GetStringIndex(S, e) { |
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if (Type(S) !== 'String') { |
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throw new $TypeError('Assertion failed: `S` must be a String'); |
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} |
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if (!IsIntegralNumber(e) || e < 0) { |
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throw new $TypeError('Assertion failed: `e` must be a non-negative integer'); |
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} |
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if (S === '') { |
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return 0; |
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} |
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var codepoints = StringToCodePoints(S); |
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var eUTF = e >= codepoints.length ? S.length : $indexOf(S, codepoints[e]); |
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return eUTF; |
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};
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