<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style>
body{margin: 0; padding: 0;}
#ulList{background-color: green;}
li{list-style: none;border-bottom: 1px dashed white;height: 30px;line-height: 30px;}
</style>
<script>
window.onload = function(){
var oUl = document.getElementById('ulList');
var aLi = oUl.getElementsByTagName('li');
//计算每种商品的数量和价格
//在使用getElementsByTagName时,如果只有一个标签存在 不要忘记后面[0];
function calcEach(oli){
var aInp = oli.getElementsByTagName('input');
var oStrong = oli.getElementsByTagName('strong')[0];
var oEm = oli.getElementsByTagName('em')[0];
var oSpan = oli.getElementsByTagName('span')[0];
var eachNum = oStrong.innerHTML;
var eachMoney = parseFloat(oEm.innerHTML);
aInp[1].onclick = function(){
eachNum++;
oStrong.innerHTML = eachNum;
oSpan.innerHTML = (eachNum*eachMoney).toFixed(2)+'元';
calcTotal('strong','allNum');
calcTotal('span','allMoney');
}
aInp[0].onclick = function(){
eachNum--;
if(eachNum<0){
eachNum=0;
}
oStrong.innerHTML = eachNum;
oSpan.innerHTML = (eachNum*eachMoney).toFixed(2)+'元';
calcTotal('strong','allNum');
calcTotal('span','allMoney');
}
}
for(var i = 0;i<aLi.length;i++){
calcEach(aLi[i]);
}
//计算购物者购买的总量和总价格
function calcTotal(tagName,id){
var arr = [];
var reg = /^[0-9]*[1-9][0-9]*$/;
var num = 0;
for(var i=0;i<aLi.length;i++){
var aTagName = aLi[i].getElementsByTagName(tagName);
for(var j=0;j<aTagName.length;j++){
arr.push(aTagName[j]);
}
}
for(var i = 0;i<arr.length;i++){
num +=parseFloat(arr[i].innerHTML);
}
if(reg.test(num)){
document.getElementById(id).innerHTML = num;
}else{
document.getElementById(id).innerHTML = num.toFixed(2);
}
}
};
</script>
</head>
<body>
<ul id="ulList">
<li>
<input type="button" value="-"/>
<strong>0</strong>
<input type="button" value="+"/>
单价:<em>12.51元</em>
小计:<span>0元</span>
</li>
<li>
<input type="button" value="-"/>
<strong>0</strong>
<input type="button" value="+"/>
单价:<em>8.52元</em>
小计:<span>0元</span>
</li>
<li>
<input type="button" value="-"/>
<strong>0</strong>
<input type="button" value="+"/>
单价:<em>10.57元</em>
小计:<span>0元</span>
</li>
</ul>
<p style="font-size: 20px;font-family: arial;color: red; background-color: black;">商品合计:<span id="allNum"><strong>0</strong></span>件,共花费了:<span id="allMoney">0</span>元</p>
</body>
</html>
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