<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var a;
var txt1=document.getElementById("txt1").value;
var txt2=document.getElementById("txt2").value;
var select=document.getElementById("select").value;
switch(select){
case "+":
a = parseFloat(txt1) + parseFloat(txt2);
break;
case "-":
a = parseFloat(txt1) - parseFloat(txt2);
break;
case "*":
a = parseFloat(txt1) * parseFloat(txt2);
break;
case "/":
a = parseFloat(txt1) / parseFloat(txt2);
}
document.getElementById("fruit").value=a;
}
</script>
</head>
<body>
<input type='text' id='txt1'/>
<select id='select'>
<option value='+'>+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select>
<input type='text' id='txt2'/>
<input type='button' value=' = ' onclick="count()"/> <!--通过 = 按钮来调用创建的函数,得到结果-->
<input type='text' id='fruit' />
</body>
</html>
打开App,阅读手记