JSFiddle - React, Tailwind, and code Playground

by Per Ă…strand

HTML

<table align="center">
    <tr>
        <td align="center">Quantity:</td>
        <td colspan="2"></td>
    </tr>
    <tr>
        <td><input type="number" min="64" max="9999" name="quantity" /></td>
        <td>&nbsp;&nbsp;@&nbsp;&nbsp;$345.50/per item&nbsp;&nbsp;=&nbsp;&nbsp;</td>
        <td data-product-price="345.50"></td>
    </tr>
    
    <tr>
        <td align="center">Quantity:</td>
        <td colspan="2"></td>
    </tr>
    <tr>
        <td><input type="number" min="64" max="9999" name="quantity" /></td>
        <td>&nbsp;&nbsp;@&nbsp;&nbsp;$49.95/per item&nbsp;&nbsp;=&nbsp;&nbsp;</td>
        <td data-product-price="49.95"></td>
    </tr>
    
    <tr>
        <td align="center">Quantity:</td>
        <td colspan="2"></td>
    </tr>
    <tr>
        <td><input type="number" min="64" max="9999" name="quantity" /></td>
        <td>&nbsp;&nbsp;@&nbsp;&nbsp;$100/per item&nbsp;&nbsp;=&nbsp;&nbsp;</td>
        <td data-product-price="100"></td>
    </tr>
</table>

JavaScript

$(function(){
    $("input[name='quantity']").on("input", function(){
        var $outputCell = $(this).parent().siblings("[data-product-price]").eq(0); 
		$outputCell.html(+$outputCell.data("product-price") * +$(this).val());
    });
});