30 lines
766 B
JavaScript
30 lines
766 B
JavaScript
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'use strict';
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var callBound = require('call-bind/callBound');
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var $TypeError = require('es-errors/type');
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var StringToCodePoints = require('./StringToCodePoints');
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var isInteger = require('../helpers/isInteger');
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var $indexOf = callBound('String.prototype.indexOf');
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// https://262.ecma-international.org/13.0/#sec-getstringindex
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module.exports = function GetStringIndex(S, e) {
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if (typeof 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 (!isInteger(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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