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下面将展示小型计算器代码及效果图：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>迷你计算器</title>
<style type="text/css">
.box {
width: 500px;
height: 200px;
background-color: #efefef;
border: 1px solid lightgray;
text-align: center;
margin: 20px auto;
color: #636363;
border-radius: 15px;
box-shadow: 2px 2px 2px #999;
}
table {
margin: auto;
/*参考线*/
/*border: 1px solid red; */
}
td {
width: 100px;
height: 30px;
padding: 5px 10px;
}
input, select {
width: 100%;
height:100%;
border:none;
text-align: left;
padding-left: 15px;
/*background-color: cyan;*/
}
button {
width: 100%;
height: 100%;
border: none;
background-color: skyblue;
color: white;
}
button:hover {
cursor: pointer;
background-color: coral;
width: 105%;
height: 105%;
}
</style>
</head>
<body>
<div class="box">
<h2>小小计算器</h2>
<form>
<table>
<tr>
<td><input type="text" name="opt1" placeholder="操作数1" autofocus></td>
<td>
<select name="option">
<option value="null">请选择操作</option>
<option value="add"> + </option>
<option value="sub"> - </option>
<option value="mul"> * </option>
<option value="div"> / </option>
</select>
</td>
<td><input type="text" name="opt2" placeholder="操作数2"></td>
<td><button type="button">计算</button></td>
</tr>
<tr>
<td colspan="2" align="right"><h3>结果:</h3></td>
<td colspan="2" align="left"><h3 id="result"></h3></td>
</tr>
</table>
</form>
</div>
<script>
var opt1=document.getElementsByName('opt1')[0];
var opt2=document.getElementsByName('opt2')[0];
var opt=document.getElementsByName('option')[0];
var btn=document.getElementsByTagName('button')[0];
var result=document.getElementById('result');
btn.onclick=function(){
var data1=0;
var data2=0;
if(opt1.value.length===0){
alert('操作不能为空');
opt1.focus();
return false;
}else if(isNaN(opt1.value)){
alert('必须为数字');
opt1.focus();
return false;
}else if(opt2.value.length===0){
alert('操作不能为空');
opt2.focus();
return false;
}else if(isNaN(opt2.value)){
alert('必须为数字');
opt2.focus();
return false;
}else {
data1=parseFloat(opt1.value);
data2=parseFloat(opt2.value);
}
var option =opt.value;
var temp=0;
var flag='';
switch (option) {
case 'null':
alert('请选择操作类型');
return false;
case 'add':
flag='+';
temp=data1+data2;
break;
case 'sub':
flag='-';
temp=data1-data2;
break;
case 'mul':
flag='*';
temp=data1*data2;
break;
case 'div':
flag='/';
if(data2===0){
alert('除数不能为0，请重新输入');
opt2.focus();
return false;
}else {
temp = data1 / data2;
temp = Math.round(temp * 100) / 100;
}
break;
}
var str='<span style="color: coral">';
str+=data1+flag+data2+'='+temp;
str+='</span>';
result.innerHTML=str;
}
</script>
</body>
</html>点击 "运行实例" 按钮查看在线实例
