JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" size="5" id="value1" name="value1" class="value" />
<input type="text" size="5" id="value2" name="value2" class="value" />
<input type="text" size="5" id="total" readonly="readonly" class="bckground" name="total" />

JavaScript

jQuery(document).ready(function ($) {
    var $total = $('#total'),
        $value = $('.value');
    $value.on('input', function (e) {
        var total = 1;
        $value.each(function (index, elem) {
            if (!Number.isNaN(parseInt(this.value, 10))) total = total * parseInt(this.value, 10);
        });
        $total.val(total);
    });
});