JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="InvoiceAmount">
<input type="text" id="InvoicePrice">
<p id="AnotherElement">Test</p>

JavaScript

$("#InvoiceAmount").bind('keyup keydown keypress',function()
        {
            // Your calculations here
            var invoiceMultiplied = $(this).val() * $(this).val();
            // Update another element with the result
            $('#AnotherElement').html(invoiceMultiplied);
        }
    );