效果如下：
all code:
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>原生js购物车</title>
<style>
h1{text-align:center;}
table{margin:0 auto;width:60%;border:2px solid #aaa;
border-collapse:collapse;}
table th, table td {
border:2px solid #aaa;
padding:5px;
}
</style>
</head>
<body>
<h1>真划算</h1>
<table>
<tr>
<th>商品</th>
<th>单价(元)</th>
<th>颜色</th>
<th>库存</th>
<th>好评率</th>
<th>操作</th>
</tr>
<tr>
<td>罗技M185鼠标</td>
<td>80</td>
<td>黑色</td>
<td>893</td>
<td>98%</td>
<td align="center">
<input type="button" value="加入购物车" onclick="add_shoppingcart(this);"/>
</td>
</tr>
<tr>
<td>微软X470键盘</td>
<td>150</td>
<td>黑色</td>
<td>9028</td>
<td>96%</td>
<td align="center">
<input type="button" value="加入购物车" onclick="add_shoppingcart(this);"/>
</td>
</tr>
<tr>
<td>洛克iphone6手机壳</td>
<td>60</td>
<td>透明</td>
<td>672</td>
<td>99%</td>
<td align="center">
<input type="button" value="加入购物车" onclick="add_shoppingcart(this);"/>
</td>
</tr>
<tr>
<td>蓝牙耳机</td>
<td>100</td>
<td>蓝色</td>
<td>8937</td>
<td>95%</td>
<td align="center">
<input type="button" value="加入购物车" onclick="add_shoppingcart(this);"/>
</td>
</tr>
<tr>
<td>金士顿U盘</td>
<td>70</td>
<td>红色</td>
<td>482</td>
<td>100%</td>
<td align="center">
<input type="button" value="加入购物车" onclick="add_shoppingcart(this);"/>
</td>
</tr>
</table>
<h1>购物车</h1>
<table>
<thead>
<tr>
<th>商品</th>
<th>单价(元)</th>
<th>数量</th>
<th>金额(元)</th>
<th>删除</th>
</tr>
</thead>
<tbody id="goods">
<!--
<tr>
<td>罗技M185鼠标</td>
<td>80</td>
<td align="center">
<input type="button" value="-"/>
<input type="text" size="3" readonly value="1"/>
<input type="button" value="+"/>
</td>
<td>80</td>
<td align="center"><input type="button" value="x" onclick="delete();"/></td>
</tr>
-->
</tbody>
<tfoot>
<tr>
<td colspan="3" align="right">总计</td>
<td id="total"></td>
<td></td>
</tr>
</tfoot>
</table>
</body>
</html>
<script>
function add_shoppingcart(btn) {
var tr = btn.parentNode.parentNode;
var tds = tr.getElementsByTagName("td");
var name = tds[0].innerHTML;
var price = tds[1].innerHTML;
var tbody = document.getElementById("goods");
var row = tbody.insertRow();
row.innerHTML =
'<td>'+name+'</td>'+
'<td>'+price+'</td>'+
'<td align="center">'+
'<input type="button" value="-" onclick="change(this, -1);"/> '+
'<input type="text" size="3" readonly value="1"/> '+
'<input type="button" value="+" onclick="change(this, 1);"/> '+
'</td>'+
'<td>'+price+'</td>'+
'<td align="center"><input type="button" value="x" onclick="del(this);"/></td>';
total();
}
function del(btn) {
var tr = btn.parentNode.parentNode;
tr.parentNode.removeChild(tr);
total();
}
function change(btn, n) {
var inputs = btn.parentNode.getElementsByTagName("input");
var amount = parseInt(inputs[1].value);
if(amount<=1 && n<0) {
return;
}
inputs[1].value = amount + n;
amount = inputs[1].value;
var tr = btn.parentNode.parentNode;
var tds = tr.getElementsByTagName("td");
var price = parseFloat(tds[1].innerHTML);
var m = price*amount;
tds[3].innerHTML = m;
total();
}
function total() {
var tbody = document.getElementById("goods");
var trs = tbody.getElementsByTagName("tr");
var sum = 0;
for(var i=0;i<trs.length;i++) {
var td = trs[i].getElementsByTagName("td");
var m = td[3].innerHTML;
sum += parseFloat(m);
}
var total = document.getElementById("total");
total.innerHTML = sum;
}
</script>