JSFiddle - React, Tailwind, and code Playground

by cgough

HTML

<form onsubmit="javascript: alert('sending...'); return false;">
<input type="text" id="screen" />
<div id="keypad">
    <button>7</button>
    <button>8</button>
    <button>9</button>
    <br />
    <button>4</button>
    <button>5</button>
    <button>6</button>
    <br />
    <button>1</button>
    <button>2</button>
    <button>3</button>
    <br />
    <button>0</button>
</div>
</form>

JavaScript

window.onload = function () {
        var screen  = document.getElementById('screen'),
            keypad  = document.getElementById('keypad'),
            buttons = keypad.getElementsByTagName('button');
        for (var i = 0; i < buttons.length; i++) {
            buttons[i].onclick = function () {
                screen.value = screen.value + this.innerHTML;
                return false;
            };
        }
    };