Web/JavaScript/Reference/Global objects/String/codePointAt

The codePointAt() method returns a non-negative integer that is the Unicode code point value.

Syntax

str.codePointAt(pos)

Parameters

pos: Position of an element in str to return the code point value from.

Return value

A number representing the code point value of the character at the given pos. If there is no element at pos, returns undefined.

Description

If there is no element at the specified position, undefined is returned. If no UTF-16 surrogate pair begins at pos, the code unit at pos is returned.

Examples

Using codePointAt()

'ABC'.codePointAt(1)           // 66
'\uD800\uDC00'.codePointAt(0)  // 65536

'XYZ'.codePointAt(42)          // undefined

Looping with codePointAt()

for (let codePoint of '\ud83d\udc0e\ud83d\udc71\u2764') {
   console.log(codePoint.codePointAt(0).toString(16)) 
} 
// '1f40e', '1f471', '2764'

Polyfill

The following extends Strings to include the codePointAt() function as specified in ECMAScript 2015 for browsers without native support.

/*! https://mths.be/codepointat v0.2.0 by @mathias */
if (!String.prototype.codePointAt) {
  (function() {
    'use strict'; // needed to support `apply`/`call` with `undefined`/`null`
    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 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
          // https://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
          return (first - 0xD800) * 0x400 + second - 0xDC00 + 0x10000;
        }
      }
      return first;
    };
    if (defineProperty) {
      defineProperty(String.prototype, 'codePointAt', {
        'value': codePointAt,
        'configurable': true,
        'writable': true
      });
    } else {
      String.prototype.codePointAt = codePointAt;
    }
  }());
}

Specifications

Specification
ECMAScript (ECMA-262)The definition of 'String.prototype.codePointAt' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`codePointAt`	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 41	Chrome Android Full support 41	Firefox Android Full support 29	Opera Android Full support 28	Safari iOS Full support 10	Samsung Internet Android Full support 4.0	nodejs Full support 4.0.0 Full support 4.0.0 Full support 0.12 Disabled' Disabled' From version 0.12: this feature is behind the `--harmony` runtime flag.

Legend

Full support: Full support
No support: No support
User must explicitly enable this feature.': User must explicitly enable this feature.