String Character Length: Difference between revisions

JavaScript encodes strings in UTF-16, which represents each character with one or two 16-bit values. The most commonly used characters are represented by one 16-bit value, while rarer ones like some mathematical symbols are represented by two.

JavaScript has no built-in way to determine how many characters are in a string. However, if the string only contains commonly used characters, the number of characters will be equal to the number of 16-bit values used to represent the characters.

var str1 = "Hello, world!";

var len1 = str1.length; //13

var str2 = "\uD834\uDD2A"; //U+1D12A represented by a UTF-16 surrogate pair

var len2 = str2.length; //2