循环语句
程序中进行有规律的重复性操作，需要用到循环语句。
for循环
for(var i=0;i<len;i++)
{
......
}
while循环
var i=0;
while(i<8){
......
i++;
}
数组去重
var aList = [1,2,3,4,4,3,2,1,2,3,4,5,6,5,5,3,3,4,2,1];
var aList2 = [];
for(var i=0;i<aList.length;i++)
{
if(aList.indexOf(aList[i])==i)
{
aList2.push(aList[i]);
}
}
alert(aList2);一个计数器的代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>计算器</title>
<script type="text/javascript">
window.onload = function(){
var oInput01 = document.getElementById('input01');
var oInput02 = document.getElementById('input02');
var oFuhao = document.getElementById('fuhao');
var oBtn = document.getElementById('btn');
oBtn.onclick = function(){
var num01 = oInput01.value;
var num02 = oInput02.value;
var fuhao = oFuhao.value;
if(num01=="" || num02==""){
alert('输入框不能为空！');
return;
}
if(isNaN(num01) || isNaN(num02)){
alert('请输入数字！');
return;
}
switch(fuhao){
case '0':
alert((parseFloat(num01)*100+parseFloat(num02)*100)/100);
break;
case '1':
alert((parseFloat(num01)*100-parseFloat(num02)*100)/100);
break;
case '2':
alert(((parseFloat(num01)*100)*(parseFloat(num02)*100))/10000);
break;
case '3':
alert((parseFloat(num01)*100)/(parseFloat(num02)*100));
break;
}
}
}
</script>
</head>
<body>
<h1>计算器</h1>
<input type="text" name="" id="input01">
<select id="fuhao">
<option value="0">+</option>
<option value="1">-</option>
<option value="2">*</option>
<option value="3">/</option>
</select>
<input type="text" name="" id="input02">
<input type="button" name="" value="计算" id="btn">
</body>
</html>