<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>计算器</title>
<script type="text/javascript">
window.onload = function(){
var oInput1 = document.getElementById('input1');
var oInput2 = document.getElementById('input2');
var oSelect = document.getElementById('select');
var oBtn = document.getElementById('btn');
oBtn.onclick = function(){
var val1 = oInput1.value;
var val2 = oInput2.value;
//不做此判断会弹出“NaN,除了数字不能填写其他”
if(val1=="" || val2==""){
alert('输入框不能为空！');
return;
}
if(isNaN(val1) || isNaN(val2)){
alert('请输入数字！');
return;
}
switch(oSelect.value){
case '0':
alert((parseFloat(val1)*100 + parseFloat(val2)*100)/100);
break;
case '1':
alert((parseFloat(val1)*100 - parseFloat(val2)*100)/100);
break;
case '2':
alert((parseFloat(val1)*100) * (parseFloat(val2)*100)/10000);
break;
case '3':
alert((parseFloat(val1)*100) / (parseFloat(val2)*100));
break;
}
}
}
</script>
</head>
<body>
<h1>计算器</h1>
<input type="text" name="" id="input1" />
<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="input2" />
<input type="button" name="" value="计算" id="btn" />
</body>
</html>
