react-native/Libraries/polyfills/String.prototype.es6.js

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/**
* Copyright (c) 2013-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @providesModule String.prototype.es6
* @polyfill
* @nolint
*/
/* eslint-disable strict, no-extend-native, no-bitwise */
/*
* NOTE: We use (Number(x) || 0) to replace NaN values with zero.
*/
if (!String.prototype.startsWith) {
String.prototype.startsWith = function(search) {
'use strict';
if (this == null) {
throw TypeError();
}
var string = String(this);
var pos = arguments.length > 1 ?
(Number(arguments[1]) || 0) : 0;
var start = Math.min(Math.max(pos, 0), string.length);
return string.indexOf(String(search), pos) === start;
};
}
if (!String.prototype.endsWith) {
String.prototype.endsWith = function(search) {
'use strict';
if (this == null) {
throw TypeError();
}
var string = String(this);
var stringLength = string.length;
var searchString = String(search);
var pos = arguments.length > 1 ?
(Number(arguments[1]) || 0) : stringLength;
var end = Math.min(Math.max(pos, 0), stringLength);
var start = end - searchString.length;
if (start < 0) {
return false;
}
return string.lastIndexOf(searchString, start) === start;
};
}
if (!String.prototype.repeat) {
String.prototype.repeat = function(count) {
'use strict';
if (this == null) {
throw TypeError();
}
var string = String(this);
count = Number(count) || 0;
if (count < 0 || count === Infinity) {
throw RangeError();
}
if (count === 1) {
return string;
}
var result = '';
while (count) {
if (count & 1) {
result += string;
}
if ((count >>= 1)) {
string += string;
}
}
return result;
};
}
if (!String.prototype.includes) {
String.prototype.includes = function(search, start) {
'use strict';
if (typeof start !== 'number') {
start = 0;
}
if (start + search.length > this.length) {
return false;
} else {
return this.indexOf(search, start) !== -1;
}
};
}
if (!String.prototype.codePointAt) {
String.prototype.codePointAt = function(position) {
if (this == null) {
throw TypeError();
}
var string = String(this);
var size = string.length;
// `ToInteger`
var index = position ? Number(position) : 0;
if (Number.isNaN(index)) {
index = 0;
}
// Account for out-of-bounds indices:
if (index < 0 || index >= size) {
return undefined;
}
// Get the first code unit
var first = string.charCodeAt(index);
var second;
if (
// check if its the start of a surrogate pair
first >= 0xd800 &&
first <= 0xdbff && // high surrogate
size > index + 1 // there is a next code unit
) {
second = string.charCodeAt(index + 1);
if (second >= 0xdc00 && second <= 0xdfff) {
// low surrogate
// http://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
return (first - 0xd800) * 0x400 + second - 0xdc00 + 0x10000;
}
}
return first;
};
}