静态
String.fromCodePoint()
method returns a string created by using the specified sequence of code points.
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
String.fromCodePoint(num1[, ...[, numN]])
num1
, ...,
numN
A sequence of code points.
A string created by using the specified sequence of code points.
RangeError
is thrown if an invalid Unicode code point is given (e.g.
"RangeError: NaN is not a valid code point"
).
This method returns a string (and
not
a
String
对象)。
因为
fromCodePoint()
is a static method of
String
, you must call it as
String.fromCodePoint()
, rather than as a method of a
String
object you created.
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()
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
| 规范 |
|---|
|
ECMAScript (ECMA-262)
The definition of 'String.fromCodePoint' in that specification. |
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.
更新 GitHub 上的兼容性数据| Desktop | Mobile | Server | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
fromCodePoint
|
Chrome 41 | Edge 12 | Firefox 29 | IE No | Opera 28 | Safari 10 | WebView Android 41 | Chrome Android 41 | Firefox Android 29 | Opera Android 28 | Safari iOS 10 | Samsung Internet Android 4.0 |
nodejs
4.0.0
|
完整支持
不支持
用户必须明确启用此特征。
String.fromCharCode()
String.prototype.charAt()
String.prototype.codePointAt()
String.prototype.charCodeAt()
String
String.fromCharCode()
String.fromCodePoint()
String.prototype.anchor()
String.prototype.big()
String.prototype.blink()
String.prototype.bold()
String.prototype.charAt()
String.prototype.charCodeAt()
String.prototype.codePointAt()
String.prototype.concat()
String.prototype.endsWith()
String.prototype.fixed()
String.prototype.fontcolor()
String.prototype.fontsize()
String.prototype.includes()
String.prototype.indexOf()
String.prototype.italics()
String.prototype.lastIndexOf()
String.prototype.link()
String.prototype.localeCompare()
String.prototype.match()
String.prototype.matchAll()
String.prototype.normalize()
String.prototype.padEnd()
String.prototype.padStart()
String.prototype.repeat()
String.prototype.replace()
String.prototype.replaceAll()
String.prototype.search()
String.prototype.slice()
String.prototype.small()
String.prototype.split()
String.prototype.startsWith()
String.prototype.strike()
String.prototype.sub()
String.prototype.substr()
String.prototype.substring()
String.prototype.sup()
String.prototype.toLocaleLowerCase()
String.prototype.toLocaleUpperCase()
String.prototype.toLowerCase()
String.prototype.toSource()
String.prototype.toString()
String.prototype.toUpperCase()
String.prototype.trim()
String.prototype.trimEnd()
String.prototype.trimStart()
String.prototype.valueOf()
String.prototype[@@iterator]()
String.raw()
Function
Object
Object.prototype.__defineGetter__()
Object.prototype.__defineSetter__()
Object.prototype.__lookupGetter__()
Object.prototype.__lookupSetter__()
Object.prototype.hasOwnProperty()
Object.prototype.isPrototypeOf()
Object.prototype.propertyIsEnumerable()
Object.prototype.toLocaleString()
Object.prototype.toSource()
Object.prototype.toString()
Object.prototype.valueOf()
Object.setPrototypeOf()