Question

Live Demo: http://jsfiddle.net/thisizmonster/DveuB/

How can I change this so that the input only allows the characters A-Z, a-z, 0-9 while typing, without using a regular expression?

Answer 1

Assuming you also want to accept spaces:

$("#user").keypress(function(event){
    var ew = event.which;
    if(ew == 32)
        return true;
    if(48 <= ew && ew <= 57)
        return true;
    if(65 <= ew && ew <= 90)
        return true;
    if(97 <= ew && ew <= 122)
        return true;
    return false;
});

If you don’t want to accept spaces then remove the if(ew == 32) return true;

JSFiddle