How to allow numbers, backspace, delete, left and right arrow keys in the html text?

Question

I am using following javascript code which I think should only allow numbers, backspace, delet, left arrow and right arrow keys in textbox, but it is also allowing alphabets. I

Answer 1

I modified his code a bit, so you can just add a class to an input

$(".numberonly").keydown(function(e){
    // Number Only
    if (e.keyCode == 8 || e.keyCode == 46
       || e.keyCode == 37 || e.keyCode == 39) {
          return true;
      }
      else if ( e.keyCode < 48 || e.keyCode > 57 ) {
        e.preventDefault();
      }
  });

add class to an input