循环函数document.getElementById（）

Posted 2021-03-19

所以我使用了三个唯一的ID“titleselected0”，“titleselected1”，“titleselected2”。每个都有一个onclick函数，它运行一个函数“myFunction0”，“myFunction1”，“myFunction2”。我正在用它来改变造型。我的问题是我是否可以使用循环所以我只需要使用一个函数而不是三个函数？

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
        <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/js/bootstrap.min.js"></script>
        <style type="text/css">.collapse {
           display: none;
           }
           .collapse.in {
           display: block;
           }
           .title {
           background-color: #005FAA;
           border: none;
           border-radius: 0;
           padding: 30px;
           }
           .title:hover {
           background-color: #009cde;
           border: none;
           border-radius: 0;
           padding: 30px;
           }
           .container{
           margin-top:25px;
           float:left; 
           width: 32%; 
           margin-right: 2%;
           }
           .container:last-child{
           margin-right:0px;
           width:32%;}
           @media only screen and (max-width: 800px) {
           .container{
           margin-top:15px;
           width: 100%;
           }
           .container:last-child{
           margin-top:15px;
           width: 100%;
           }
           }
           .titleselected{
           background-color: #009cde;
           border:none; 
           border-radius:0; 
           padding: 30px;
           }
        </style>
        <div>
           <div class="container">
              <div class="title" data-toggle="collapse" href="#collapse" id="titleselected0" onclick="myFunction0()">
                 <h4><a href="#collapse" style="color:white; text-decoration:none; text-align:center;">System Information</a></h4>
              </div>
              <div class="collapse" id="collapse" style="background-color:#005FAA;transition: width 200ms ease-out, height 200ms ease-out;">
                 <div style="color:white; padding: 30px;border:none;">
                    <p><strong>TestingTestingTestingTestingTestingTestingTesting</strong></p>
                    <ul>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                    </ul>
                    <p><strong>TestingTestingTestingTestingTestingTestingTesting: </strong></p>
                    <ul>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                    </ul>
                 </div>
              </div>
           </div>
           <div class="container">
              <div class="title" data-toggle="collapse" href="#collapse2" id="titleselected1" onclick="myFunction1()">
                 <h4><a href="#collapse2" style="color:white;text-decoration:none;text-align:center;">Product Specification</a></h4>
              </div>
              <div class="collapse" id="collapse2" style="background-color:#005FAA;transition: width 200ms ease-out, height 200ms ease-out;">
                 <div style="color:white; padding: 30px;border:none;">
                    <p><strong>TestingTestingTestingTestingTestingTestingTesting:</strong></p>
                    <ul>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                    </ul>
                 </div>
              </div>
           </div>
           <div class="container">
              <div class="title" data-toggle="collapse" href="#collapse3" id="titleselected2" onclick="myFunction2()">
                 <h4><a href="#collapse3" style="color:white;text-decoration:none;text-align:center;">Case Study</a></h4>
              </div>
              <div class="collapse" id="collapse3" style="background-color:#005FAA;transition: width 200ms ease-out, height 200ms ease-out;">
                 <div style="color:white; padding: 30px;border:none;">
                    <p><strong>TestingTestingTestingTestingTestingTestingTesting: </strong></p>
                    <ul>
                       <li>TestingTestingTestingTestingTestingTestingTesting</li>
                       <li>TestingTestingTestingTestingTestingTestingTesting <a href="http://portfolio.cpl.co.uk/CIBSE/201904/40/">appeared in the CIBSE Journal</a></li>
                    </ul>
                 </div>
              </div>
           </div>
        </div>
        <script>
           function myFunction0() {
              var element = document.getElementById("titleselected0");
              element.classList.toggle("titleselected");
           }
           
           function myFunction1() {
              var element = document.getElementById("titleselected1");
              element.classList.toggle("titleselected");
           }
           
           function myFunction2() {
              var element = document.getElementById("titleselected2");
              element.classList.toggle("titleselected");
           }
           
           
        </script>

答案

这些元素已经有class的title，所以你可以循环遍历所有.title元素并附加监听器：

document.querySelectorAll('.title').forEach((element) => {
  element.addEventListener('click', () => {
    element.classList.toggle("titleselected");
  });
});

（随意删除所有ids和内联属性onclick处理程序 - 最好用javascript而不是html附加监听器）

您还可以在包含所有.titles的容器上使用事件委派：

<div class="container-for-all">
   <div class="container">
     ...
   </div>
   <div class="container">
     ...
   </div>
   <!-- etc -->

和

document.querySelector('.container-for-all').addEventListener('click', ({ target }) => {
  const closestTitle = target.closest('.title');
  if (!closestTitle) {
    return;
  }
  closestTitle.classList.toggle('titleselected');
});