Restricting an input box to only numbers 0-9 [duplicate]

Answer 1

You could use an input with the HTML5 number type

<input type="number" />

or javascript, as an input with a number type doesn't really limit input to numbers only :

document.getElementById('numbersonly').addEventListener('keydown', function(e) {
    var key   = e.keyCode ? e.keyCode : e.which;

    if (!( [8, 9, 13, 27, 46, 110, 190].indexOf(key) !== -1 ||
         (key == 65 && ( e.ctrlKey || e.metaKey  ) ) || 
         (key >= 35 && key <= 40) ||
         (key >= 48 && key <= 57 && !(e.shiftKey || e.altKey)) ||
         (key >= 96 && key <= 105)
       )) e.preventDefault();
});

FIDDLE

Answer 2

Using HTML5

<input type="number">

You can also use Modernizr for backwards compatibility