JSFiddle - React, Tailwind, and code Playground
by rajeevRF
HTML
<form action="">
<input type="number" name="quantity" id="quantity" />
<input type="number" name="amount" id="amount" readonly />
<input type="submit" value="Submit">
</form>
JavaScript
$(document).ready(function(){
$('#quantity').keyup(function(){
var qty = $('#quantity').val();
$('#amount').val(qty * 50);
});
});