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Commit Description:
announcement on top menu bar
Commit Description:
announcement on top menu bar
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node_modules/es-abstract/2016/AdvanceStringIndex.js | 45 lines | 1.2 KiB | application/javascript | JavascriptLexer |
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'use strict';
var GetIntrinsic = require('../GetIntrinsic');
var IsInteger = require('./IsInteger');
var Type = require('./Type');
var MAX_SAFE_INTEGER = require('../helpers/maxSafeInteger');
var $TypeError = GetIntrinsic('%TypeError%');
var $charCodeAt = require('../helpers/callBound')('String.prototype.charCodeAt');
// https://ecma-international.org/ecma-262/6.0/#sec-advancestringindex
module.exports = function AdvanceStringIndex(S, index, unicode) {
if (Type(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 (Type(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 (first < 0xD800 || first > 0xDBFF) {
return index + 1;
}
var second = $charCodeAt(S, index + 1);
if (second < 0xDC00 || second > 0xDFFF) {
return index + 1;
}
return index + 2;
};