计算器
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>switch练习2</title>
<script type="text/javascript">
window.onload = function(){
var js = document.getElementById('js')
js.onclick = function(){
while (true){
var in1 = document.getElementById('in1').value;
var in2 = document.getElementById('in2').value;
var st1 = document.getElementById('st1').value;
in1 = parseInt(in1);
in2 = parseInt(in2);
if (isNaN(in1) || isNaN(in2)){
alert('输入不合法');
break
}else{
if (st1 == 'a'){
var b = in1+in2;
alert(in1+'+'+in2+'='+b);
break
}else if (st1 == 'b'){
var b = in1-in2;
alert(in1+'-'+in2+'='+b);
break
}else if (st1 == 'c'){
var b = in1*in2;
alert(in1+'*'+in2+'='+b);
break
}else if (st1 == 'd'){
var b = in1/in2;
alert(in1+'/'+in2+'='+b);
break
}
}
}
}
}
</script>
</head>
<body>
<input type="text" name="" id="in1">
<select id="st1">
<option value="a">+</option>
<option value="b">-</option>
<option value="c">*</option>
<option value="d">/</option>
</select>
<input type="text" name="" id="in2">
<input type="button" name="" value="计算" id="js">
</body>
</html>
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