JSFiddle - React, Tailwind, and code Playground

HTML

<input class="numbersOnly" id="n1" type="text" value="100"><br><br>
<input class="numbersOnly" id="n2" type="text" value="200">

CSS

body {padding:10px}

numbersOnly {padding:5px}

JavaScript

$(document).ready(function() {
    $(".numbersOnly").keydown(function(event) {
        // Allow: backspace, delete, tab, escape, and enter
        if (event.keyCode == 46 || event.keyCode == 8 || event.keyCode == 9 || event.keyCode == 27 || event.keyCode == 13 ||
        // Allow: Ctrl+A
        (event.keyCode == 65 && event.ctrlKey === true) ||
        // Allow: home, end, left, right
        (event.keyCode >= 35 && event.keyCode <= 39)) {
            // let it happen, don't do anything
            return;
        }
        else {
            // Ensure that it is a number and stop the keypress
            if (event.shiftKey || (event.keyCode < 48 || event.keyCode > 57) && (event.keyCode < 96 || event.keyCode > 105)) {
                event.preventDefault();
            }
        }
    });
});