Greasy Fork

Hi, what about using isNaN instead of keys and keys.indexOf?

(function() {
    'use strict';

    (window.opera ? document.body : document).addEventListener('keydown', function(e) {
        if (isNaN(e.key) || e.isComposing || e.ctrlKey || e.altKey) return;
        e.cancelBubble = true;
        e.stopImmediatePropagation();
        return false;
    }, !window.opera);
})();

I realised it also needs a e.key === ' ' condition

if (e.key === ' ' || isNaN(e.key) || e.isComposing || e.ctrlKey || e.altKey) return;`

The source code is based on a very old stackoverflow post

• No need to detect window.opera any more.
• return false in a event listener callback is a totally wrong concept. No effect on it.
• Setting cancelBubble is already depreciated.

Obviously this script is just created by newbie.

(function () {
    const keys = new Set('0123456789'.split(''));
    // keys.add(' '); // You can add other keys. Check in https://www.toptal.com/developers/keycode
    document.addEventListener('keydown', function (e) {
        if (keys.has(e.key) || e.isComposing || e.ctrlKey || e.altKey) return;
        e.stopPropagation();
        e.stopImmediatePropagation();
    }, true);
})();