The static String.fromCodePoint()
method returns a string created by using the specified sequence of code points.
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Syntax
String.fromCodePoint(num1[, ...[, numN]])
Parameters
num1, ..., numN
- A sequence of code points.
Return value
A string created by using the specified sequence of code points.
Exceptions
- A
RangeError
is thrown if an invalid Unicode code point is given (e.g. "RangeError: NaN is not a valid code point").
Description
This method returns a string and not a String
object.
Because fromCodePoint()
is a static method of String
, you always use it as String.fromCodePoint()
, rather than as a method of a String
object you created.
Examples
Using 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
Compared to fromCharCode()
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
Polyfill
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));
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'String.fromCodePoint' in that specification. |
Standard | Initial definition. |
ECMAScript Latest Draft (ECMA-262) The definition of 'String.fromCodePoint' in that specification. |
Draft |
Browser compatibility
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.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
fromCodePoint | Chrome Full support 41 | Edge Full support 12 | Firefox Full support 29 | IE No support No | Opera Full support 28 | Safari Full support 10 | WebView Android Full support Yes | Chrome Android Full support 41 | Firefox Android Full support 29 | Opera Android Full support Yes | Safari iOS Full support 10 | Samsung Internet Android Full support Yes | nodejs
Full support
4.0.0
|
Legend
- Full support
- Full support
- No support
- No support
- User must explicitly enable this feature.
- User must explicitly enable this feature.