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String.prototype.codePointAt()
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since septiembre de 2015.
El métodocodePointAt() devuelve un entero no negativo que equivale al valor Unicode code point del carácter.
Sintaxis
str.codePointAt(indice)
Parámetros
indiceÍndice del carácter en la cadena del que se quiere obtener el valor del Unicode code point.
Valor de retorno
Un número que equivale al valor code point del carácter especificado en el índice de la cadena; devuelveundefined si no se encuentra carácter en la posición especifica.
Description
If there is no element at the specified position,undefined is returned. If no UTF-16 surrogate pair begins atpos, the code unit atpos is returned.
Examples
UsingcodePointAt()
"ABC".codePointAt(1); // 66"\uD800\uDC00".codePointAt(0); // 65536"XYZ".codePointAt(42); // undefinedPolyfill
The following extends Strings to include thecodePointAt() function as specified in ECMAScript 2015 for browsers not supporting it natively.
/*! http://mths.be/codepointat v0.1.0 by @mathias */if (!String.prototype.codePointAt) { (function () { "use strict"; // needed to support `apply`/`call` with `undefined`/`null` var codePointAt = function (position) { if (this == null) { throw TypeError(); } var string = String(this); var size = string.length; // `ToInteger` var index = position ? Number(position) : 0; if (index != index) { // better `isNaN` 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 it’s 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; }; if (Object.defineProperty) { Object.defineProperty(String.prototype, "codePointAt", { value: codePointAt, configurable: true, writable: true, }); } else { String.prototype.codePointAt = codePointAt; } })();}Especificaciones
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-string.prototype.codepointat |