Use: String.fromCharCode(charCode)
e.g:
var str1=String.fromCharCode(65)
will return “A”
charCodeAt(index) returns the char code for the character at a given
index position within a string (zero based index).
So if you want the char code for a single character:-
var nCharCode="A".charCodeAt(0);
will return 65
See a list of Character Codes Here