--- title: String.fromCodePoint() slug: Web/JavaScript/Reference/Global_Objects/String/fromCodePoint translation_of: Web/JavaScript/Reference/Global_Objects/String/fromCodePoint original_slug: Web/JavaScript/Referencje/Obiekty/String/fromCodePoint ---
The static String.fromCodePoint()
method returns a string created by using the specified sequence of code points.
String.fromCodePoint(num1[, ...[, numN]])
num1, ..., numN
A string created by using the specified sequence of code points.
"RangeError: NaN is not a valid code point"
).This method returns a string (and not a {{jsxref("String")}} object).
Because fromCodePoint()
is a static method of {{jsxref("String")}}, you must call it as String.fromCodePoint()
, rather than as a method of a {{jsxref("String")}} object you created.
The String.fromCodePoint()
method has been added to ECMAScript 2015 and may not be supported in all web browsers or environments yet.
Use the code below for a polyfill:
if (!String.fromCodePoint) (function(stringFromCharCode) { var fromCodePoint = function(_) { var codeUnits = [], codeLen = 0, result = ""; for (var index=0, len = arguments.length; index !== len; ++index) { var codePoint = +arguments[index]; // correctly handles all cases including `NaN`, `-Infinity`, `+Infinity` // The surrounding `!(...)` is required to correctly handle `NaN` cases // The (codePoint>>>0) === codePoint clause handles decimals and negatives if (!(codePoint < 0x10FFFF && (codePoint>>>0) === codePoint)) throw RangeError("Invalid code point: " + codePoint); if (codePoint <= 0xFFFF) { // BMP code point codeLen = codeUnits.push(codePoint); } else { // Astral code point; split in surrogate halves // https://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae codePoint -= 0x10000; codeLen = codeUnits.push( (codePoint >> 10) + 0xD800, // highSurrogate (codePoint % 0x400) + 0xDC00 // lowSurrogate ); } if (codeLen >= 0x3fff) { result += stringFromCharCode.apply(null, codeUnits); codeUnits.length = 0; } } return result + stringFromCharCode.apply(null, codeUnits); }; try { // IE 8 only supports `Object.defineProperty` on DOM elements Object.defineProperty(String, "fromCodePoint", { "value": fromCodePoint, "configurable": true, "writable": true }); } catch(e) { String.fromCodePoint = fromCodePoint; } }(String.fromCharCode));
fromCodePoint()
Valid input:
String.fromCodePoint(42); // "*" String.fromCodePoint(65, 90); // "AZ" String.fromCodePoint(0x404); // "\u0404" == "Є" String.fromCodePoint(0x2F804); // "\uD87E\uDC04" String.fromCodePoint(194564); // "\uD87E\uDC04" String.fromCodePoint(0x1D306, 0x61, 0x1D307); // "\uD834\uDF06a\uD834\uDF07"
Invalid input:
String.fromCodePoint('_'); // RangeError String.fromCodePoint(Infinity); // RangeError String.fromCodePoint(-1); // RangeError String.fromCodePoint(3.14); // RangeError String.fromCodePoint(3e-2); // RangeError String.fromCodePoint(NaN); // RangeError
fromCharCode()
{{jsxref("String.fromCharCode()")}} cannot return supplementary characters (i.e. code points 0x010000
– 0x10FFFF
) by specifying their code point. Instead, it requires the UTF-16 surrogate pair in order to return a supplementary character:
String.fromCharCode(0xD83C, 0xDF03); // Code Point U+1F303 "Night with String.fromCharCode(55356, 57091); // Stars" == "\uD83C\uDF03"
String.fromCodePoint()
, on the other hand, can return 4-byte supplementary characters, as well as the more common 2-byte BMP characters, by specifying their code point (which is equivalent to the UTF-32 code unit):
String.fromCodePoint(0x1F303); // or 127747 in decimal
Specification |
---|
{{SpecName('ESDraft', '#sec-string.fromcodepoint', 'String.fromCodePoint')}} |
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
{{Compat("javascript.builtins.String.fromCodePoint")}}