js实现计算器功能

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本文实例为大家分享了js实现计算器功能的具体代码，供大家参考，具体内容如下

知识点

eval() 函数可计算某个字符串，并执行其中的的 JavaScript 代码。

代码如下

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>js计算器</title>
 <link href="../css/计算器.css" rel="stylesheet">
</head>
<body>
<h1 class="h1">计算器</h1>
 <div class="box">
  <form name="calculator">
   <input type="button" id="clear" class="btn other" value="C">
   <input type="text" id="display">
   <br/>
   <input type="button" class="btn number" value="7" onclick="get(this.value);">
   <input type="button" class="btn number" value="8" onclick="get(this.value);">
   <input type="button" class="btn number" value="9" onclick="get(this.value);">
   <input type="button" class="btn operator" value="+" onclick="get(this.value);">
   <br/>
   <input type="button" class="btn number" value="4" onclick="get(this.value);">
   <input type="button" class="btn number" value="5" onclick="get(this.value);">
   <input type="button" class="btn number" value="6" onclick="get(this.value);">
   <input type="button" class="btn operator" value="*" onclick="get(this.value);">
   <br/>
   <input type="button" class="btn number" value="1" onclick="get(this.value);">
   <input type="button" class="btn number" value="2" onclick="get(this.value);">
   <input type="button" class="btn number" value="3" onclick="get(this.value);">
   <input type="button" class="btn operator" value="-" onclick="get(this.value);">
   <br/>
   <input type="button" class="btn number" value="0" onclick="get(this.value);">
   <input type="button" class="btn operator" value="." onclick="get(this.value);">
   <input type="button" class="btn operator" value="/" onclick="get(this.value);">
   <input type="button" class="btn other" value="=" onclick="calculates();">
  </form>
 <div>
<script src="../js/计算器.js">
</script>
</body>
</html>

.h1{
 position: relative;
 color:blueviolet;
 font-size:50px;
 text-align: center;
 top:50px;
}
.box{
 width:500px;
 position: relative;
 top: 100px;
 left:50%;
 margin-left: -250px;
 text-align: center;
 background: #495678;
 padding:80px 0;
 border-radius: 20px;
 box-shadow: 4px 4px #3d4a65;
}
.btn{
 background:rgba(255,192,203,0.8);
 border: 1px solid pink;
 cursor:pointer;
 outline:none;
 font-size:30px;
 margin:10px 15px;
 height: 70px;
 width: 70px;
 box-shadow: 0 5px #1a1313de;
}
.btn:active{
 transform: translateY(2px);
}
.btn:first-child{
 margin-left:-300px;
}
#display{
 overflow: hidden;
 box-sizing: border-box;
 padding-right:18px;
 text-align: right;
 outline: none;
 border:1px solid #4caf50;
 color:yellow;
 font-size: 30px;
 width:280px;
 position: absolute;
 height: 50px;
 top:95px;
 right:55px;
 background-color: #4caf50;
}
#display,.btn,.box{
 border-radius:35px;
}
.operator{
 background:orange;
}
.other{
 background:white;
}

//清空
  document.getElementById("clear").addEventListener("click",function(){
  document.getElementById("display").value="";
 });
//运算
 function get(value) {
  document.getElementById("display").value+=value;
 }
 //结果
 function calculates() {
  var result=0;
  result=document.getElementById("display").value;
  document.getElementById("display").value = eval(result);
 }

效果图