JS键盘版计算器的制作方法

核心代码实现

<!DOCTYPE html>
<html>
 
 <head>
 <meta charset="UTF-8">
 <title></title>
 <style type="text/css">
 #show {
 width: 232px;
 height: 80px;
 color: white;
 border-radius: 5px 5px 0 0;
 background-color: rgba(127, 128, 127, 1);
 text-align: right;
 border: none;
 font-size: 45px;
 outline: none;
 }
 
 table {
 border: 1px solid black;
 border-collapse: collapse;
 width: 234px;
 text-align: center;
 font-size: 30px;
 }
 
 td {
 height: 55px;
 width: 57.5px;
 background-color: wheat;
 }
 
 td:active {
 background-color: coral;
 }
 
 .aperation {
 background-color: rgb(245, 146, 62);
 color: white;
 }
 
 #ape {
 background-color: wheat;
 color: #000000;
 }
 </style>
 </head>
 
 <body>
 <div id="">
 <input type="" id="show" />
 <table border="1">
 <tr>
  <td id="clear">AC</td>
  <td>+/-</td>
  <td class="aperation" id="ape">%</td>
  <td class="aperation">/</td>
 </tr>
 <tr>
  <td class="num">7</td>
  <td class="num">8</td>
  <td class="num">9</td>
  <td class="aperation">*</td>
 </tr>
 <tr>
  <td class="num">4</td>
  <td class="num">5</td>
  <td class="num">6</td>
  <td class="aperation">-</td>
 </tr>
 <tr>
  <td class="num">1</td>
  <td class="num">2</td>
  <td class="num">3</td>
  <td class="aperation">+</td>
 </tr>
 <tr>
  <td colspan="2" class="num">0</td>
 
  <td>.</td>
  <td class="aperation" id="result">=</td>
 </tr>
 </table>
 </div>
 </body>
 <script type="text/javascript">
 //获取数字的集合
 var nums = document.getElementsByClassName("num");
 //获取操作符的集合
 var options = document.getElementsByClassName("aperation");
 //获取等号
 var result = document.getElementById("result");
 //获取归0
 var clear = document.getElementById("clear");
 //获取展示框
 var show = document.getElementById("show");
 //声明用于保存内容的三个变量
 var numValue = ""; //存储数字
 var optionC = ""; //存储操作符
 var numTemp = ""; //存储暂存值
 
 //点击数字键时 触发事件
 for(var i = 0; i < nums.length; i++) {
 nums[i].onclick = function() {
 if(numValue == "0") {
  numValue = "";
 }
 numValue += this.innerHTML;
 show.value = numValue;
 
 }
 }
 
 //点击操作键触发事件
 for(var i = 0; i < options.length - 1; i++) {
 options[i].onclick = function() {
 //先存储之前记录的数字
 numTemp = numValue;
 //记录操作符
 optionC = this.innerHTML;
 //清除原有记录的数字
 numValue = "";
 
 }
 }
 //等号操作
 result.onclick = function() {
 show.value = eval(numTemp + optionC + numValue);
 }
//清零操作
 clear.onclick = function() {
 show.value = "0";
 numValue = "";
 optionC = "";
 numTemp = "";
 }
 </script>
 
</html>