Backspace and space not working in Firefox

Question

I have the following validation to allow only numbers and a decimal in Javascript

function validate(evt) {
      var theEvent = evt || window.event;
      var key = theEvent.keyCode || theEvent.which;           
      key = String.fromCharCode( key );
      var regex = /[0-9]|\./;
      if( !regex.test(key) ) {
        theEvent.returnValue = false;
        if(theEvent.preventDefault) theEvent.preventDefault();
      }
}

I call this in my textbox element like onkeypress='validate(event)'

This code works fine in IE but when I try the same with Firefox backspace, left and right arrow keys and space does not work.

How would I fix this?

Answer 1

use keyup or keydown instead of keypress

keypress is only supposed to fire when there is a character insert

http://www.quirksmode.org/dom/events/keys.html

Answer 2

keydown function would work across all browsers. Please use keydown function and it would work!

Ex.:-

$(document).keydown(function (e){
                    if(e.keyCode == 37) // left arrow
                    {

                    //code for left arrow

                    }
                    else if(e.keyCode == 39)    // right arrow
                    {

                   //code for right arrow
                    }
                    });

Answer 3

Using key press is the right solution, but you simply need to attach the event handler by JS (which is considered better practice anyway), and use something like this:

$('#myInput').keypress(function(event){
   validate(event)
});

function validate(evt) {
  var theEvent = evt || window.event;
  var key = theEvent.keyCode || theEvent.which;           
  if (key <48 || key > 57  || key == 190)//keycode is a number between 0 and 9 or '.'
       ...
};

Answer 4

Try

    //allows number and hyphen only 
    function isNumeric(e)
    {
        var a = e.charCode;
        if(a==0){return;}
        return ((a >= 48 && a <= 57));
    }
    </script>

Firefox Backspace charcode 0.