javascript limit text input characters

Question

I am wanting to restrict the input characters for a text box to [a-z0-9_-]. However whenever if do this buttons like backspace and the arrow keys don\'t work. I have found s

Answer 1

You can press any key you like, as long as you keep the value from including anything not in the white-list.

inputelement.onkeyup=function(e){
  e=e || window.event;
  var who=e.target || e.srcElement;
  who.value= who.value.replace(/[^\w-]+/g,'');
}