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?
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;