<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>计算器作业</title>
<script type="text/javascript">
window.onload = function(){
var oInput01 = document.getElementById('input01');
var oInput02 = document.getElementById('input02');
var oSelect = document.getElementById('select');
var oBtn = document.getElementById('btn');
oBtn.onclick = function(){
var value1 = oInput01.value;
var value2 = oInput02.value;
//不做此判断会弹出“NaN”
if(value1=="" || value2==""){
alert('输入框不能为空！');
return;
}
if(isNaN(value1) || isNaN(value2)){
alert('请输入数字！');
return;
}
switch(oSelect.value){
case '0':
alert((parseFloat(value1)*100 + parseFloat(value2)*100)/100);
break;
case '1':
alert((parseFloat(value1)*100 - parseFloat(value2)*100)/100);
break;
case '2':
alert((parseFloat(value1)*100) * (parseFloat(value2)*100)/10000);
break;
case '3':
alert((parseFloat(value1)*100) / (parseFloat(value2)*100));
break;
}
}
}
</script>
</head>
<body>
<h1>计算器</h1>
<input type="text" name="" id="input01" />
<select id="select">
<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>
