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String.fromCodePoint()
Baseline
Ampliamente disponible
Esta característica está consolidada y funciona en muchos dispositivos y versiones de navegador. Está disponible en todos los navegadores desde septiembre de 2015.
El método estatico String.fromCodePoint() devuelve una cadena creada por una secuencia de puntos de codigo.
String.fromCodePoint(num1[, ...[, numN]])
RangeError-
A RangeError is thrown if an invalid Unicode code point is given (e.g. "RangeError: NaN is not a valid code point").
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.
js
String.fromCodePoint(42); // "*"
String.fromCodePoint(65, 90); // "AZ"
String.fromCodePoint(0x404); // "\u0404"
String.fromCodePoint(0x2f804); // "\uD87E\uDC04"
String.fromCodePoint(194564); // "\uD87E\uDC04"
String.fromCodePoint(0x1d306, 0x61, 0x1d307); // "\uD834\uDF06a\uD834\uDF07"
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
js
// String.fromCharCode() alone cannot get the character at such a high code point
// The following, on the other hand, can return a 4-byte character as well as the
// usual 2-byte ones (i.e., it can return a single character which actually has
// a string length of 2 instead of 1!)
console.log(String.fromCodePoint(0x2f804)); // or 194564 in decimal
The String.fromCodePoint method has been added to the ECMAScript standard in version 6 and may not be supported in all web browsers or environments yet. Use the code below for a polyfill:
js
/*! http://mths.be/fromcodepoint v0.1.0 by @mathias */
if (!String.fromCodePoint) {
(function () {
var defineProperty = (function () {
// IE 8 only supports `Object.defineProperty` on DOM elements
try {
var object = {};
var $defineProperty = Object.defineProperty;
var result = $defineProperty(object, object, object) && $defineProperty;
} catch (error) {}
return result;
})();
var stringFromCharCode = String.fromCharCode;
var floor = Math.floor;
var fromCodePoint = function () {
var MAX_SIZE = 0x4000;
var codeUnits = [];
var highSurrogate;
var lowSurrogate;
var index = -1;
var length = arguments.length;
if (!length) {
return "";
}
var result = "";
while (++index < length) {
var codePoint = Number(arguments[index]);
if (
!isFinite(codePoint) || // `NaN`, `+Infinity`, or `-Infinity`
codePoint < 0 || // not a valid Unicode code point
codePoint > 0x10ffff || // not a valid Unicode code point
floor(codePoint) != codePoint // not an integer
) {
throw RangeError("Invalid code point: " + codePoint);
}
if (codePoint <= 0xffff) {
// BMP code point
codeUnits.push(codePoint);
} else {
// Astral code point; split in surrogate halves
// http://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
codePoint -= 0x10000;
highSurrogate = (codePoint >> 10) + 0xd800;
lowSurrogate = (codePoint % 0x400) + 0xdc00;
codeUnits.push(highSurrogate, lowSurrogate);
}
if (index + 1 == length || codeUnits.length > MAX_SIZE) {
result += stringFromCharCode.apply(null, codeUnits);
codeUnits.length = 0;
}
}
return result;
};
if (defineProperty) {
defineProperty(String, "fromCodePoint", {
value: fromCodePoint,
configurable: true,
writable: true,
});
} else {
String.fromCodePoint = fromCodePoint;
}
})();
}