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JS实现简易计算器

网络编程 2021-07-04 15:02www.168986.cn编程入门
这篇文章主要为大家详细介绍了JS实现简易计算器功能，文中示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下

用JS实现简易计算器，供大家参考，具体内容如下

创建结构和样式

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>Document</title>
 <style>
  body{
   margin:0;
   padding:0;
   background-color: #abcdef;
  }
  .cal{
   width:560px;
   height:100px;
   margin:0 auto;
   padding-:300px;
  }
 </style>
</head>
<body>

 <div class="cal">
  <p>
   <input type="text" class="num1" value="1">
   <span class="sign">+</span>
   <input type="text" class="num2" value="1">
   <span>=</span>
   <span class="res">2</span>
  </p>
  <p>
   <input type="button" value="+">
   <input type="button" value="-">
   <input type="button" value="">
   <input type="button" value="/">
  </p>   
 </div>
<script>


</script>

</body>
</html>

然后添加Java script

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>Document</title>
 <style>
  body{
   margin:0;
   padding:0;
   background-color: #abcdef;
  }
  .cal{
   width:560px;
   height:100px;
   margin:0 auto;
   padding-:300px;
  }
 </style>
</head>
<body>

 <div class="cal">
  <p>
   <input type="text" class="num1" value="1">
   <span class="sign">+</span>
   <input type="text" class="num2" value="1">
   <span>=</span>
   <span class="res">2</span>
  </p>
  <p>
   <input type="button" value="+" class="btn">
   <input type="button" value="-" class="btn">
   <input type="button" value="" class="btn">
   <input type="button" value="/" class="btn">
  </p>   
 </div>

<script>
 var cal=document.querySelector(".cal");
 var num1=cal.querySelector(".num1");
 var num2=cal.querySelector(".num2");
 var sign=cal.querySelector(".sign");
 var res=cal.querySelector(".res");

 var btns=cal.querySelectorAll(".btn");

 btns[0].onclick=add;
 btns[1].onclick=subtract;
 btns[2].onclick=multiply;
 btns[3].onclick=divide;

 function add(){
  sign.innerHTML="+";
  //由于DOM获取到的值都是字符串形式，进行操作时需要先转为number类型
  res.innerHTML=Number(num1.value)+Number(num2.value);
 }
 function subtract(){
  sign.innerHTML="-";
  res.innerHTML=Number(num1.value)-Number(num2.value);
 }
 function multiply(){
  sign.innerHTML="";
  res.innerHTML=Number(num1.value)Number(num2.value); 
 }
 function divide(){
  sign.innerHTML="/";
  res.innerHTML=Number(num1.value)/Number(num2.value); 
 }
</script>

</body>
</html>

代码的优化

循环实现绑定

给一个外部接口，用于新增运算

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>Document</title>
 <style>
  body{
   margin:0;
   padding:0;
   background-color: #abcdef;
  }
  .cal{
   width:560px;
   height:100px;
   margin:0 auto;
   padding-:300px;
  }
 </style>
</head>
<body>

 <div class="cal">
  <p>
   <input type="text" class="num1" value="1">
   <span class="sign">+</span>
   <input type="text" class="num2" value="1">
   <span>=</span>
   <span class="res">2</span>
  </p>
  <p>
   <input type="button" value="+" class="btn" title="add">
   <input type="button" value="-" class="btn" title="subtract">
   <input type="button" value="" class="btn" title="multiply">
   <input type="button" value="/" class="btn" title="divide">
   <input type="button" value="%" class="btn" title="mod">
  </p>   
 </div>

<script>
 var cal=document.querySelector(".cal");
 var num1=cal.querySelector(".num1");
 var num2=cal.querySelector(".num2");
 var sign=cal.querySelector(".sign");
 var res=cal.querySelector(".res");

 var btns=cal.querySelectorAll(".btn");

 //给每个按钮绑定事件
 for(var i=0;i<btns.length;i++){
  operate(i);
 }

 //运算函数
 function operate(i){
  var op=btns[i].value;//获取运算
  var opName=btns[i].title;//获取运算名
  //绑定事件
  btns[i].onclick=function(){
   sign.innerHTML=op;
   res.innerHTML=operation[opName](Number(num1.value),Number(num2.value));
  }
 }

 var operation={
  add:function(n1,n2){
   return n1+n2;
  },
  subtract:function(n1,n2){
   return n1-n2;
  },
  multiply:function(n1,n2){
   return n1n2;
  },
  divide:function(n1,n2){
   return n1/n2;
  },
  //给一个新增运算的接口
  addOperation:function(name,fn){
   //如果该运算不存在
   if(!this.name){
    this[name]=fn;
   }
  }
 }

 //新增取余运算
 operation.addOperation("mod",function(n1,n2){
  return n1%n2;
 });
</script>

</body>
</html>

这样就圆满完成咯

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持狼蚁SEO。

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