JavaScript实现简易计算器的完整代码与逻辑解析

核心代码实现

<!DOCTYPE html>
<html>
 <head>
  <meta charset="UTF-8">
  <title></title>
  <style type="text/css">
   #div1{
    margin:20px auto;
    width:420px;
    height:490px;
    background-color:#E8E8E8;
    border:1px solid #ccc;
    border-radius:5px;
    }
   .div2{
    width:410px;
    height:60px;
    border:1px solid #ccc;
    margin:5px auto;
    border-radius:5px;
    text-align:right;
    font-size:30px;
    background-color:white;
    padding-top:10px;
       } 
   
   .div3{
    width:410px;
    height:60px;
    margin:5px auto;
    float:left;
   }
   .div13{
    float:left;
    width:70px;
    height:60px;
    border:1px solid #ccc;
    background-color: ghostwhite;
    margin-left:8px;
    text-align:center;
    font-size:30px;
    color:deepskyblue;
    border-radius:5px;
    cursor:default;
    padding-top:10px;
    box-shadow:4px 3px 3px #CCCCCC;
    }
   .div133{width:160px;}
   .top{margin-top:10px;margin-left:10px;} 
   .color{color:black;}
   .top1{margin-top:20px;margin-left:10px;}
   .top2{margin-top:30px;margin-left:10px;}
   .top3{margin-top:40px ;margin-left:10px;}
   .div23{float:left;}
   .div33{float:left;}
  </style>
 </head>
 <body>
  <div id="div1">
   <div class="div2" id="input"><b>0</b></div>
   <div class="div3">
    <div class="div13" onclick="w(' ')"><b>C</b></div>
    <div class="div13"onclick="w('opposite')"><b>+/-</b></div>
    <div class="div13" onclick="w('percent')"><b>%</b></div>
    <div class="div13 div133" onclick="w('backspace')"><b>←</b></div>
   </div>
    <div class="div3">
     <div class="div13 top color" onclick="a('7')"><b>7</b></div>
     <div class="div13 top color" onclick="a('8')"><b>8</b></div>
     <div class="div13 top color" onclick="a('9')"><b>9</b></div>
     <div class="div13 top " onclick="a('+')"><b>+</b></div>
     <div class="div13 top " onclick="a('-')"><b>-</b></div>
     
    </div>
    <div class="div3">
     <div class="div13 top1 color" onclick="a('4')"><b>4</b></div>
     <div class="div13 top1 color"onclick="a('5')"><b>5</b></div>
     <div class="div13 top1 color" onclick="a('6')"><b>6</b></div>
     <div class="div13 top1" onclick="a('*')"><b>×</b></div>
     <div class="div13 top1" onclick="a('/')"><b>÷</b></div>
     </div>
     <div class="div3">
     <div class="div13 top2 color" onclick="a('1')"><b>1</b></div>
     <div class="div13 top2 color" onclick="a('2')"><b>2</b></div>
     <div class="div13 top2 color"onclick="a('3')"><b>3</b></div>
     <div class="div13 top2"onclick="w('pow')"><b>x<sup>2</sup></b></div>
     <div class="div13 top2" onclick="w('sqrt')"><b>√</b></div>
     </div>
     <div class="div3">
      <div class="div13 top3 color" onclick="a('0')"><b>0</b></div>
      <div class="div13 top3"onclick="a('.')"><b>.</b></div>
      <div class="div13 top3"onclick="e('=')"><b>=</b></div>
     </div>
     
     </div>
    <script>
     input=document.getElementById("input");
    s="";
     function a(v)
     {
     s=s+v;
     input.innerHTML=s; 
     }
    function e(v)
     {
     input.innerHTML=eval(s);
     }
    
    function w(type)
     { 
     switch(type)
     { case ' ':s='';break;
      case 'opposite':s=-s;break;
      case 'percent':s=s/100;break;
      case 'pow':s=Math.pow(s,2);break;
      case 'sqrt':s=Math.sqrt(s);break;
      case 'backspace':s=s.substr(s,s.length-1);// case  'backspace':s=s.substring(0,s.length-1);
      }
      input.innerHTML=s; 
      } 
      
     
     
   
     
     
     
    </script>
   
   
   
  
 </body>
</html>