原生js-购物车案例（一）整体思路和实施步骤
原生js-购物车案例（一）整体思路和实施步骤
在准备写购物车之前补充一个小小的知识点（有关table的一个api）：
<body>
<table id="tab">
<tbody>
<tr>
<td>333</td>
</tr>
</tbody>
</table>
</body>
获取上述的td中的值我们可以这样操作
<script>
var tab = document.getElementById("tab");
alert(tab.getElementsByTagName("tbody")[0]
.getElementsByTagName("tr")[0]
.getElementsByTagName("td")[0].innerHTML);
</script>
有点小麻烦，我们可以不用获取tbody，tr，td节点，像下面的代码这么做
var tab = document.getElementById("tab");
alert(tab.tBodies[0].rows[0].cells[0].innerHTML);
//tbody ===> tBodies
//tr===>rows
//td ==>cells
</script>
另外还要注意一点：
在一个table中，设置tr和td，尽管不设置tbody 也会默认在table和tr中间生成一个tbody，而且要注意，只有设置tr td的时候会出现tbody（设置tr th不会默认生成tbody）
补充这个知识点的原因，是因为我们的html部分使用表格做的，用这个知识点操作更方便。
附上css和html部分：
css部分
* {
margin: 0;
padding: 0;
}
a {
color: #666;
text-decoration: none;
}
body {
padding: 20px;
color: #666;
}
.fl{
float: left;
}
.fr {
float: right;
}
table {
border-collapse: collapse;
border-spacing: 0;
border: 0;
text-align: center;
width: 937px;
}
th, td {
border: 1px solid #CADEFF;
}
th {
background: #e2f2ff;
border-top: 3px solid #a7cbff;
height: 30px;
}
td {
padding: 10px;
color: #444;
}
tbody tr:hover {
background: RGB(238,246,255);
}
.checkbox {
width: 60px;
}
.goods {
width: 300px;
}
.goods span {
width: 180px;
margin-top: 20px;
text-align: left;
float: left;
}
.price {
width: 130px;
}
.count {
width: 90px;
}
.count .add, .count input, .count .reduce {
float: left;
margin-right: -1px;
position: relative;
z-index: 0;
}
.count .add, .count .reduce {
height: 23px;
width: 17px;
border: 1px solid #e5e5e5;
background: #f0f0f0;
text-align: center;
line-height: 23px;
color: #444;
}
.count .add:hover, .count .reduce:hover {
color: #f50;
z-index: 3;
border-color: #f60;
cursor: pointer;
}
.count input {
width: 50px;
height: 15px;
line-height: 15px;
border: 1px solid #aaa;
color: #343434;
text-align: center;
padding: 4px 0;
background-color: #fff;
z-index: 2;
}
.subtotal {
width: 150px;
color: red;
font-weight: bold;
}
.operation {
width: 80px;
}
.operation span:hover, a:hover {
cursor: pointer;
color: red;
text-decoration: underline;
}
img {
width: 100px;
height: 80px;
/*border: 1px solid #ccc;*/
margin-right: 10px;
float: left;
}
.foot {
width: 935px;
margin-top: 10px;
color: #666;
height: 48px;
border: 1px solid #c8c8c8;
background-color: #eaeaea;
background-image:linear-gradient(RGB(241,241,241),RGB(226,226,226));
position: relative;
z-index: 8;
}
.foot div, .foot a {
line-height: 48px;
height: 48px;
}
.foot .select-all {
width: 100px;
height: 48px;
line-height: 48px;
padding-left: 5px;
color: #666;
}
.foot .closing {
border-left: 1px solid #c8c8c8;
width: 100px;
text-align: center;
color: #000;
font-weight: bold;
background: RGB(238,238,238);
cursor: pointer;
}
.foot .total{
margin: 0 20px;
cursor: pointer;
}
.foot #priceTotal, .foot #selectedTotal {
color: red;
font-family: "Microsoft Yahei";
font-weight: bold;
}
.foot .selected {
cursor: pointer;
}
.foot .selected .arrow {
position: relative;
top:-3px;
margin-left: 3px;
}
.foot .selected .down {
position: relative;
top:3px;
display: none;
}
.show .selected .down {
display: inline;
}
.show .selected .up {
display: none;
}
.foot .selected:hover .arrow {
color: red;
}
.foot .selected-view {
width: 935px;
border: 1px solid #c8c8c8;
position: absolute;
height: auto;
background: #ffffff;
z-index: 9;
bottom: 48px;
left: -1px;
display:none;
}
.show .selected-view {
display: block;
}
.foot .selected-view div{
height: auto;
}
.foot .selected-view .arrow {
font-size: 16px;
line-height: 100%;
color:#c8c8c8;
position: absolute;
right: 330px;
bottom: -9px;
}
.foot .selected-view .arrow span {
color: #ffffff;
position: absolute;
left: 0px;
bottom: 1px;
}
#selectedViewList {
padding: 20px;
margin-bottom: -20px;
}
#selectedViewList div{
display: inline-block;
position: relative;
width: 100px;
height: 80px;
border: 1px solid #ccc;
margin: 10px;
}
#selectedViewList div span {
display: none;
color: #ffffff;
font-size: 12px;
position: absolute;
top: 0px;
right: 0px;
width: 60px;
height: 18px;
line-height: 18px;
text-align: center;
background: RGBA(0,0,0,.5);
cursor: pointer;
}
#selectedViewList div:hover span {
display: block;
}
html部分
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>demo</title>
<link rel="stylesheet" href="css/style.css"/>
</head>
<body>
<table id="cartTable">
<thead>
<tr>
<th><label><input class="check-all check" type="checkbox"/> 全选</label></th>
<th>商品</th>
<th>单价</th>
<th>数量</th>
<th>小计</th>
<th>操作</th>
</tr>
</thead>
<tbody>
<tr>
<td class="checkbox"><input class="check-one check" type="checkbox"/></td>
<td class="goods"><img src="images/1.jpg" alt=""/><span>Casio/卡西欧 EX-TR350</span></td>
<td class="price">5999.88</td>
<td class="count"><span class="reduce"></span><input class="count-input" type="text" value="1"/><span class="add">+</span></td>
<td class="subtotal">5999.88</td>
<td class="operation"><span class="delete">删除</span></td>
</tr>
<tr>
<td class="checkbox"><input class="check-one check" type="checkbox"/></td>
<td class="goods"><img src="images/2.jpg" alt=""/><span>Canon/佳能 PowerShot SX50 HS</span></td>
<td class="price">3888.50</td>
<td class="count"><span class="reduce"></span><input class="count-input" type="text" value="1"/><span class="add">+</span></td>
<td class="subtotal">3888.50</td>
<td class="operation"><span class="delete">删除</span></td>
</tr>
<tr>
<td class="checkbox"><input class="check-one check" type="checkbox"/></td>
<td class="goods"><img src="images/3.jpg" alt=""/><span>Sony/索尼 DSC-WX300</span></td>
<td class="price">1428.50</td>
<td class="count"><span class="reduce"></span><input class="count-input" type="text" value="1"/><span class="add">+</span></td>
<td class="subtotal">1428.50</td>
<td class="operation"><span class="delete">删除</span></td>
</tr>
<tr>
<td class="checkbox"><input class="check-one check" type="checkbox"/></td>
<td class="goods"><img src="images/4.jpg" alt=""/><span>Fujifilm/富士 instax mini 25</span></td>
<td class="price">640.60</td>
<td class="count"><span class="reduce"></span><input class="count-input" type="text" value="1"/><span class="add">+</span></td>
<td class="subtotal">640.60</td>
<td class="operation"><span class="delete">删除</span></td>
</tr>
</tbody>
</table>
<div class="foot" id="foot">
<label class="fl select-all"><input type="checkbox" class="check-all check"/> 全选</label>
<a class="fl delete" id="deleteAll" href="javascript:;">删除</a>
<div class="fr closing">结 算</div>
<div class="fr total">合计：￥<span id="priceTotal">0.00</span></div>
<div class="fr selected" id="selected">已选商品<span id="selectedTotal">0</span>件<span class="arrow up">︽</span><span class="arrow down">︾</span></div>
<div class="selected-view">
<div id="selectedViewList" class="clearfix">
<div><img src="images/1.jpg"><span>取消选择</span></div>
</div>
<span class="arrow">◆<span>◆</span></span>
</div>
</div>
<script type="text/javascript" src="js/script.js"></script>
</body>
</html>
接下来我们会从
1》如果复选框选中，把对应的数量和价格，放入到结算中
2》结算功能，都在什么地方使用（数量增加或者减少）(删除)(单价*数量=总价) ==》封装成一个函数实现
3》点击按钮,数量增加，小计值发生变化 删除
4》已选商品的添加=》取消选择
这四个点（js），逐步完善购物车功能。