<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>加、减、乘、除运算</title>
<script type="text/javascript">
function calculate(){
var num1 = parseFloat(document.getElementById("num1").value);
var num2 = parseFloat(document.getElementById("num2").value);
var val = document.getElementById("value").value;
if(val=="+"){
document.getElementById("num3").value = num1 + num2 ;
}
else if(val=="-"){
document.getElementById("num3").value = num1 - num2 ;
}
else if(val=="*"){
document.getElementById("num3").value = num1 * num2 ;
}
else if(val=="/"){
document.getElementById("num3").value = num1 / num2 ;
}
};
</script>
</head>
<!--
要求采用面向对象的方式定义函数，实现加、减、乘、除运算功能。
-->
<body>
<form>
<center>
<fieldset style="height:200px;">
<legend>请输入要运算的数</legend>
<input type="text" id="num1" value="" />
<select name="cal" id="value">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select>
<input type="text" id="num2" value=""/>=
<input type="text" id="num3" value=""/>
<input type="button" value="提交" onClick="calculate()"/>
</fieldset>
</center>
</form>
</body>
</html>