<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<input class="s1" type="text" name="" id="" />
<select name="" id="">
<option>+</option>
<option>-</option>
<option>*</option>
<option>/</option>
</select>
<input class="s2" type="text" />
<p>点击计算</p>
<h1>结果是:</h1>
</body>
<script type="text/javascript">
var s1 =document.getElementsByClassName('s1')[0];
var s2 =document.getElementsByClassName('s2')[0];
var btn=document.getElementsByTagName('p')[0];
var fh=document.getElementsByTagName('select')[0];
var result=document.getElementsByTagName('h1')[0];
btn.onclick=function(){
//获取两个参与计算的数字,并转化为number类型(因为input的value值为string,无法参与计算)
var s11=Number(s1.value);
var s22=Number(s2.value);
//获取运算符
var jieguo;
switch(fh.value){
case'+':
jieguo=s11+s22;
break;
case'-':
jieguo=s11-s22;
break;
case'*':
jieguo=s11*s22;
break;
case'/':
jieguo=s11/s22;
break;
}
result.innerHTML='结果是:'+jieguo;
}
</script>
</html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<input class="s1" type="text" name="" id="" />
<select name="" id="">
<option>+</option>
<option>-</option>
<option>*</option>
<option>/</option>
</select>
<input class="s2" type="text" />
<p>点击计算</p>
<h1>结果是:</h1>
</body>
<script type="text/javascript">
var s1 =document.getElementsByClassName('s1')[0];
var s2 =document.getElementsByClassName('s2')[0];
var btn=document.getElementsByTagName('p')[0];
var fh=document.getElementsByTagName('select')[0];
var result=document.getElementsByTagName('h1')[0];
btn.onclick=function(){
//获取两个参与计算的数字,并转化为number类型(因为input的value值为string,无法参与计算)
var s11=Number(s1.value);
var s22=Number(s2.value);
//获取运算符
var jieguo;
switch(fh.value){
case'+':
jieguo=s11+s22;
break;
case'-':
jieguo=s11-s22;
break;
case'*':
jieguo=s11*s22;
break;
case'/':
jieguo=s11/s22;
break;
}
result.innerHTML='结果是:'+jieguo;
}
</script>
</html>