JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-2.2.3.min.js"></script>
 <table id="tb" border='1'>
            <tr>
                <th>Product</th>
                <th>Price</th>
                <th>Quantity</th>
            </tr>
            <tr>
                <td>APPLE</td>
                <td>35</td>
                <td>
                    <input type='text' />
                    <button>加到購物車</button>
            </tr>
            <tr>
                <td>BANANA</td>
                <td>18</td>

                <td>
                    <input type='text' />
                    <button>加到購物車</button>
            </tr>
            <tr>
                <td>TOMATO</td>
                <td>39</td>

                <td>
                    <input type='text' />
                    <button>加到購物車</button>

            </tr>
            <tr>
                <td>ORANGE</td>
                <td>17</td>

                <td>
                    <input type='text' />
                    <button>加到購物車</button>
            </tr>
            <tr>
                <td>LEMON</td>
                <td>28</td>
                <td>
                    <input type='text' />
                    <button>加到購物車</button>
            </tr>
            <tr>
                <td>TOTAL</td>
                <td></td>
                <td colspan="2" id='total'></td>
            </tr>

        </table>

JavaScript

$(document).ready(function () {
            let totalNum = localStorage.getItem('xyz'); //從localstorage取得加總金額
            localStorage.getItem('abx'); //從localstorage取得單價乘以數量
            $('button').click(function () {
            		let total = 0;
                let price = 0;
                let qunt = 0;
            		$('#tb input').each(function(i,j){
                	 	price = parseInt($(j).parent().prev().html(),10);
                    qunt = $(j).val() || 0;
                    if(qunt < 0) qunt = 0;
                    total += price * qunt;
                });
                $('#total').text(total);
                //let qunt = $(this).prev().val(); //取得input的金額
                //localStorage.setItem('abc', qunt); //將價格記錄在localstorage
                //let pri = $(this).closest('td').prev('td').html(); //取得原本設定的單價
                //let totalNum = 0; //加總初始值是0
                //let total = qunt * pri; //單價乘以數量
                //totalNum += total; //把之前按的加總
                //$('#total').text(totalNum); //把加總的印在總額裡面
                //localStorage.setItem('xyz', $('#total').val()); //紀錄加總金額在localstorage
            })
        })