JSFiddle - React, Tailwind, and code Playground
HTML
<form>
<input id="quantity" class="qty" type="text" placeholder="quantity" />
</form>
<!--display total cost here-->
<span>The Cost is: totalcost</span>
JavaScript
var cost = 25;
/*function(updater) {
var cost = 25;
var quantity = receive quantity from the form input
var totalcost = (cost * quantity);
send total back to html document and display as total cost
*/