lix-website/themes/lix/assets/bootstrap/node_modules/es-abstract/2017/AdvanceStringIndex.js
2024-04-26 22:49:34 -06:00

44 lines
1.2 KiB
JavaScript

'use strict';
var isInteger = require('../helpers/isInteger');
var isLeadingSurrogate = require('../helpers/isLeadingSurrogate');
var isTrailingSurrogate = require('../helpers/isTrailingSurrogate');
var MAX_SAFE_INTEGER = require('../helpers/maxSafeInteger');
var $TypeError = require('es-errors/type');
var $charCodeAt = require('call-bind/callBound')('String.prototype.charCodeAt');
// https://262.ecma-international.org/6.0/#sec-advancestringindex
module.exports = function AdvanceStringIndex(S, index, unicode) {
if (typeof S !== 'string') {
throw new $TypeError('Assertion failed: `S` must be a String');
}
if (!isInteger(index) || index < 0 || index > MAX_SAFE_INTEGER) {
throw new $TypeError('Assertion failed: `length` must be an integer >= 0 and <= 2**53');
}
if (typeof unicode !== 'boolean') {
throw new $TypeError('Assertion failed: `unicode` must be a Boolean');
}
if (!unicode) {
return index + 1;
}
var length = S.length;
if ((index + 1) >= length) {
return index + 1;
}
var first = $charCodeAt(S, index);
if (!isLeadingSurrogate(first)) {
return index + 1;
}
var second = $charCodeAt(S, index + 1);
if (!isTrailingSurrogate(second)) {
return index + 1;
}
return index + 2;
};