JS String Prototype CharCodeAt

JavaScript String prototype charCodeAt

The charCodeAt() method returns the numeric Unicode value of the character at the given index (except for unicode codepoints > 0x10000).

Syntax

str.charCodeAt(index)

Parameters

index

An integer greater than or equal to 0 and less than the length of the string; if it is not a number, it defaults to 0.

MDN link | MSDN link

Description

Note that charCodeAt() will always return a value that is less than 65536. This is because the higher code points are represented by a pair of (lower valued) "surrogate" pseudo-characters which are used to comprise the real character. Because of this, in order to examine or reproduce the full character for individual characters of value 65536 and above, for such characters, it is necessary to retrieve not only charCodeAt(i), but also charCodeAt(i+1) (as if examining/reproducing a string with two letters). See example 2 and 3 below.

charCodeAt() returns NaN if the given index is less than 0 or is equal to or greater than the length of the string.

Examples

'ABC'.charCodeAt(0); // returns 65

var str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; 
document.write(str.charCodeAt(str.length - 1));

// Output: 90