JavaScript: String.fromCharCode

String.fromCharCode(codeUnit1, codeUnit2 etc)

Return a string, where each character in string has corresponding code units. Example: String.fromCharCode ( 97, 98) === "ab"

[see Character, Code Unit, Codepoint]

Each of codeUnit should be a integer from 0 to 65535 inclusive. (Note: 65535 = 2^16 -1). If it is greater than 65535, a value of modulo(codeUnit, 2^16) is used.

(it's possible to use String.fromCharCode() to create a string that contains a character with Unicode codepoint greater than 65535. You have to find the pair of 16 bits values (called surrogate pairs) to form 1 such character.)

Note: most of the time, you probably want String.fromCodePoint instead.

// convert sequence of unicode codepoint to string

console.log( 
 String.fromCharCode ( 97, 98) === "ab"
); // true

// 97 is the codepoint for letter “a”
// 98 is the codepoint for letter “b”

// String.fromCharCode won't work as expected if codepoint is greater than 65535 (that's 2^16 )

const tt = String.fromCharCode ( 128514 );

// 😂
// name: FACE WITH TEARS OF JOY
// codepoint decimal: 128514
// codepoint hexadecimal: 1f602

console.log( tt ); // prints , WRONG