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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<style type="text/css">
*{
margin: 0;padding: 0;
}
.box{
width: 600px;
height: 300px;
background-color: #ECECEC;
margin: 30px auto;
border-radius:30px ;
box-shadow: 10px 10px 10px 5px #9C9C9C;
text-align: center;
}
.main{
margin-top: 50px;
}
#inp1,#inp2,#acc{
width: 120px;
height: 30px;
border:1px solid coral;
border-radius:5px ;
}
select{
border-radius:5px ;
width: 110px;
height: 30px;
}
#acc{
background-color: coral;
}
#acc:hover{
cursor: pointer;
font-size: 1.2em;
}
.bottom{
margin-top: 50px;
}
.bottom h3,p{
text-align: center;
}
.bottom h3{
margin-bottom: 20px;
}
</style>
<title>计算器的实战案例</title>
</head>
<body>
<div class="box">
<h1>计算器</h1>
<div class="main">
<form action="" method="post">
<input type="text" name="inp1" id="inp1" value="" />
<select name="option">
<option value="null">请输入操作符</option>
<option value="add">加</option>
<option value="sub">减</option>
<option value="mul">乘</option>
<option value="div">除</option>
</select>
<input type="text" name="inp2" id="inp2" value="" />
<input type="button" name="acc" id="acc" value="计算" />
</form>
</div>
<div class="bottom">
<h3>计算结果：</h3>
<p id="results"></p>
</div>
</div>
</body>
</html>
<script type="text/javascript">
var inp1 = document.getElementById("inp1")
var inp2 =document.getElementById("inp2")
var opt = document.getElementsByName('option')[0]
var acc= document.getElementById("acc")
var results = document.getElementById("results")
acc.onclick = function(){
if(inp1.value.length==0){
alert('非法操作：第一选项不能为空')
return false
}else if(isNaN(inp1.value)){
alert('非法操作：第一选项不能为非数字')
inp1.focus()
return false
}else if(inp2.value.length==0){
alert('非法操作：第2选项不能为空')
return false
}else if(isNaN(inp2.value)){
alert('非法操作：第2选项不能为非数字')
inp1.focus()
return false
}else{
var data1 =parseFloat(inp1.value)
var data2 =parseFloat(inp2.value)
}
var temp;
var flag;
switch(opt.value){
case 'null':
alert('请正确选择操作类型')
opt.focus();
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('非法操作：除数不能为0')
inp2.focus()
return false
} else{
temp = data1 / data2
}
break
}
//results.innerHTML = data1+flag+data2+'='+temp
var str = '<span style="font-size:20px;color: coral;">'
str += data1+flag+data2+'='+temp
str += '</span>'
results.innerHTML = str
}
</script>点击 "运行实例" 按钮查看在线实例
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