com.google.javascript.jscomp.js.es6.string.codepointat.js Maven / Gradle / Ivy
/*
* Copyright 2016 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'require util/checkstringargs';
'require util/polyfill';
$jscomp.polyfill('String.prototype.codePointAt', function(orig) {
if (orig) return orig;
/**
* Returns the UTF-16 codepoint at the given index.
*
* Polyfills the instance method String.prototype.codePointAt().
*
* @this {string}
* @param {number} position
* @return {number|undefined} The codepoint.
*/
var polyfill = function(position) {
// NOTE: this is taken from v8's harmony-string.js StringCodePointAt
'use strict';
var string = $jscomp.checkStringArgs(this, null, 'codePointAt');
var size = string.length;
// Make 'position' a number (non-number coerced to NaN and then or to zero).
position = Number(position) || 0;
if (!(position >= 0 && position < size)) {
return void 0;
}
// Truncate 'position' to an integer.
position = position | 0;
var first = string.charCodeAt(position);
if (first < 0xD800 || first > 0xDBFF || position + 1 === size) {
return first;
}
var second = string.charCodeAt(position + 1);
if (second < 0xDC00 || second > 0xDFFF) {
return first;
}
return (first - 0xD800) * 0x400 + second + 0x2400;
};
return polyfill;
}, 'es6', 'es3');