JavaScript实现html购物车代码

<!DOCTYPE html>
<html >
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <script src="jquery-3.4.1.js" type="text/javascript" charset="utf-8"></script>
    <title>购物车</title>
    <style>
        input{
            width:25px;
        }
    </style>
   
</head>
<body>
    <div>
        <table  cellspacing="0" cellpadding="10px">
            <thead>
                <th><input type='checkbox'></th>
                <th>商品</th>
                <th>数量</th>
                <th>单价</th>
                <th>状态</th>
                <th>库存</th>
                <th>小计</th>
            </thead>
            <tbody>
                <tr>
                    <td><input type='checkbox'></td>
                    <td>语音电子红外体温计枪</td>
                    <td>
                        <button class="jian">-</button>
                        <input type="number" maxlength="2" value="0" disabled>
                        <button class="jia">+</button>
                    </td>
                    <td>
                        69.00
                    </td>
                    <td>
                        有货
                    </td>
                    <td>20</td>
                    <td class="xiaoji"></td>
                </tr>
                <tr>
                    <td><input type='checkbox'></td>
                    <td>儿童防晒衣</td>
                    <td>
                        <button class="jian">-</button>
                        <input type="number" maxlength="2" value="0" disabled>
                        <button class="jia">+</button>
                    </td>
                    <td>
                        109.00
                    </td>
                    <td>
                        有货
                    </td>
                    <td>20</td>
                    <td class="xiaoji"></td>
                </tr>
                <tr>
                    <td><input type='checkbox'></td>
                    <td>小黄鸭玩具</td>
                    <td>
                        <button class="jian">-</button>
                        <input type="number" maxlength="2" value="0" disabled>
                        <button class="jia">+</button>
                    </td>
                    <td>
                        9.90
                    </td>
                    <td>
                        有货
                    </td>
                    <td>20</td>
                    <td class="xiaoji"></td>
                </tr>
                <tr>
                    <td><input type='checkbox'></td>
                    <td>儿童滑板车</td>
                    <td>
                        <button class="jian">-</button>
                        <input type="number" maxlength="2" value="0" disabled>
                        <button class="jia">+</button>
                    </td>
                    <td>
                        169.00
                    </td>
                    <td>
                        有货
                    </td>
                    <td>20</td>
                    <td class="xiaoji"></td>
                </tr>
                <tr>
                    <td><input type='checkbox'></td>
                    <td>轻薄长裤</td>
                    <td>
                        <button class="jian">-</button>
                        <input type="number" maxlength="2" value="0" disabled>
                        <button class="jia">+</button>
                    </td>
                    <td>
                        39.00
                    </td>
                    <td>
                        有货
                    </td>
                    <td>20</td>
                    <td class="xiaoji"></td>
                </tr>
                <tr>
                    <td><input type='checkbox'></td>
                    <td>儿童防蚊裤</td>
                    <td>
                        <button class="jian">-</button>
                        <input type="number" maxlength="2" value="0" disabled>
                        <button class="jia">+</button>
                    </td>
                    <td>
                        29.00
                    </td>
                    <td>
                        有货
                    </td>
                    <td>20</td>
                    <td class="xiaoji"></td>
                </tr>
            </tbody>
            <tfoot>
                <tr>
                    <td colspan="5"></td>
                    <td>总计</td>
                    <td class="total"></td>
                </tr>
            </tfoot>
        </table>
    </div>
<script type="text/javascript">
        $(".jia").click(function  () {
                var num = $(this).prev().val();
                if(num==20){
                        return;
                }
                
                $(this).prev().val(parseInt(++num));
                $(this).parent().next().next().next().text(20-num) 
                 if ($(this).parent().next().next().next().text()==0) {
                        $(this).parent().next().next().text('无货')
                }
                 money ()
        })
        $(".jian").click(function  () {
                
                var num = $(this).next().val();
                if(num==0){
                        return;
                }
                $(this).next().val(parseInt(--num));
                $(this).parent().next().next().next().text(20-num)
                
                        $(this).parent().next().next().text('有货')
                        money ()
        })
        
        function money () {
                var price=$('.jia').parent().next();
                var num= $('.jia').prev();
                var xiaoji = $('.xiaoji');
                var sum = 0.0;
                for (var i=0;i<price.length;i++) {
                        var price1 = parseFloat(price.eq(i).text());
                        var num1 = parseFloat(num.eq(i).val());
                //      alert(price1*num1)
                        xiaoji.eq(i).text((price1*num1).toFixed(2))
                        sum+=price1*num1;
                }
                $('.total').text(sum.toFixed(2));
                
        }
        
</script>
</body>
</html>