JavaScript經(jīng)典案例之簡易計(jì)算器

更新時(shí)間：2020年08月24日 11:33:55 作者：@隨你所喜Z

這篇文章主要為大家詳細(xì)介紹了JavaScript經(jīng)典案例之簡易計(jì)算器，文中示例代碼介紹的非常詳細(xì)，具有一定的參考價(jià)值，感興趣的小伙伴們可以參考一下

本文實(shí)例為大家分享了JavaScript實(shí)現(xiàn)簡易計(jì)算器的具體代碼，供大家參考，具體內(nèi)容如下

效果圖：

邏輯：

1、首先通過遍歷，為所有元素添加事件； 2、各個(gè)按鈕功能分別實(shí)現(xiàn)

<!DOCTYPE html>
<html lang="en">

<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>Document</title>
</head>
<style>
 .one {
 width: 50px;
 height: 50px;
 background: #f60;
 display: inline-block;
 line-height: 50px;
 color: #fff;
 margin: 5px 5px 5px 0;
 font-size: 23px;
 text-align: center;
 cursor: pointer;
 }

 .two {
 width: 112px;
 height: 50px;
 background: #f60;
 color: #fff;
 font-size: 23px;
 display: inline-block;
 margin-top: 5px;
 text-align: center;
 line-height: 50px;
 cursor: pointer;

 }

 .tools {
 background: blue;
 cursor: pointer;

 }

 .cal {
 height: 100px;
 position: relative;
 background: #999;
 width: 228px;
 color: #fff;
 font-size: 23px;
 cursor: pointer;


 }

 .cal_content {
 position: absolute;
 bottom: 10px;
 right: 10px;
 word-break: normal;
 cursor: pointer;

 }
</style>

<body>
 <div>
 <div class="cal">
  <span class="cal_content" id="cal_content">0</span>
 </div>
 <div>
  <span class="one tools calbtn">*</span>
  <span class="one tools calbtn">/</span>
  <span class="one tools" id="del">CE</span>
  <span class="one tools" id="resset">AC</span>
 </div>
 <div>
  <span class="one calbtn">7</span>
  <span class="one calbtn">8</span>
  <span class="one calbtn">9</span>
  <span class="one tools calbtn">+</span>
 </div>
 <div>
  <span class="one calbtn"> 4</span>
  <span class="one calbtn">5</span>
  <span class="one calbtn">6</span>
  <span class="one tools calbtn">-</span>
  <!-- <span clas>-</span> -->
 </div>
 <div>
  <span class="one calbtn">1</span>
  <span class="one calbtn">2</span>
  <span class="one calbtn">3</span>
  <span class="one tools calbtn">.</span>
 </div>
 <div>
  <span class="two calbtn">0</span>
  <span class="two tools " id="fin">=</span>
 </div>
 </div>
</body>
<script>
 // 獲取標(biāo)簽
 var cal_content = document.getElementById('cal_content');
 var btn = document.getElementsByClassName('calbtn');
 var caltext = ''; //
 // 遍歷，添加事件
 for (var i = 0; i < btn.length; i++) {
 btn[i].addEventListener('click', function () {
  // this指代 當(dāng)前對象
  caltext += this.innerHTML;
  cal_content.innerHTML = caltext
 })
 }


 // 清空
 var resset = document.getElementById('resset');
 resset.addEventListener('click', function () {
 cal_content.innerHTML = '0';
 caltext = ''; //
 })

 // 刪除鍵
 var del = document.getElementById('del');
 del.addEventListener('click', function () {
 caltext = caltext.substring(0, caltext.length - 1);
 cal_content.innerHTML = caltext
 if (cal_content.innerHTML.length == 0) {
  cal_content.innerHTML = '0';
 }
 })

 //等號鍵
 var fin = document.getElementById('fin');
 fin.addEventListener('click', function () {
 // console.log(caltext)
 cal_content.innerHTML = eval(caltext);
 caltext = eval(caltext);
 // console.log(caltext)
 })


 // 鍵盤事件
 document.onkeyup = function (event) {
 var event = event || window.event;
 console.log(event.key)
 
 // 判斷F5和CTRl鍵
 if(event.keyCode==116 || event.keyCode == 17){
  return;
 }

 // 判斷是否是 回車鍵
 if (event.keyCode == 13) {
  cal_content.innerHTML = eval(caltext);
  caltext = eval(caltext);
  return;
 }
 

 caltext += event.key
 cal_content.innerHTML = caltext;
 }
</script>

</html>

總計(jì)：

1、通過對象點(diǎn)擊將元素的值鏈接在一起，最后通過**eval()函數(shù)**進(jìn)行計(jì)算，將最終結(jié)果反饋到顯示區(qū)域
2、設(shè)置一個(gè)全局表變量 *var caltext = ‘'; * 存放計(jì)算字符串
3、ondoucument.onkeyup = function(){ //代碼 } 鍵盤事件

更多計(jì)算器功能實(shí)現(xiàn)，請點(diǎn)擊專題：計(jì)算器功能匯總進(jìn)行學(xué)習(xí)

以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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