Question

I build a mechnism using JS for accepting only digits :

However I want to allow :
Delete, Backspace , left arrow , right arrow :

the solution I came up with is :

assuming I write in html (which I know its bad to send event , but lets focus on the Js code please) :

<input  onKeyPress='return CheckDigit(event)'/>



function CheckDigit(evt)
{
    var charCode = (evt.which) ? evt.which : evt.keyCode;
    if (((charCode >= 48) && (charCode <= 57)) || checkIfDelOrNavigate(charCode)))
        return true;
    return false;
}

  function checkIfDelOrNavigate(c)
    {
        if (((c == 46) || (c == 39) || (c == 37) || (c == 8))) return true;return false;
        /*46=delete , 39,37 = arrows , 8=backspace*/
    }

Questions :

• Is it the right solution ? (and if it ain’t , can you please supply an answer)

• I assume it can be changed to regex checking :

code:

 var regEx =/^[0-9]+$/;    
 isValid = regEx.test(keyChar); 
 return isValid; 

But what will be the full regEx expression ?

p.s. :
Strange but all the solutions I saw doesnt want to allow the Delete, Backspace , left arrow , right arrow chars , just the category itself.

Answer 1

I combine the answer to this question with the following check to make sure I only capture digits while allowing for non-printable characters. You’ll have to do something about the paste operation, though.

return !window.isNaN(String.fromCharCode(event.which))

See jsFiddle.