JSFiddle - React, Tailwind, and code Playground

by Admiral Potato

HTML

<form method="POST">
    $<input type="text" id="a" name="a" /><br />
    $<input type="text" id="b" name="b" /><br />
    <input type="submit" id="c" />
</form>
<div id="d">NO CHANGES</div>

JavaScript

var $doc = $(document),
    $a = $('#a'),
    $b = $('#b'),
    $d = $('#d');
var textChangeHandler = function(event) {
    if($('#a, #b').is(":focus")){
        var aVal = parseFloat($a.val()) || 0,
            bVal = parseFloat($b.val()) || 0;
        //console.log(event);
        //console.log($(document.activeElement));
        $d.html(aVal * bVal);
    }
};

$doc.on('change keydown keyup', '#a, #b', textChangeHandler);