显示/隐藏的Javascript <c:forEach> JSTL的div元素

Question

I have an JSTL for each tag as follows.

  <c:forEach items="${schedule}" var="period">
               <td>
                   <div id="friends">    
                     ${period.getFriends()}
                </div>
                 </td>
     </c:forEach>

I want to implement a button that on click will hide or show all these blocks. So far all the button does is hide or show the first element of the block. I dont know why it doesn't iterate through all the block.

<button onclick="myFunction()" class="btn btn-success btn-xs">With friend</button>
                        <button class="btn btn-danger btn-xs">Without friend</button>
                        <script>
                            function myFunction() {
                                var div = document.getElementById('friends');
                                div.innerHTML = "AFJASFAS";
                            }
                        </script>

As you can see I didn't really implement the show and hide for the buttons yet. I just tests it by adding in extra text however, this text is only added to the first div. How can i make it so it applies to all the elements?

Answer 1

That's obvious, because you are using one ID for all blocks! ID must be unique in the html page, but you have many <div id="friends"> . When you have some elements with same ID, javascript select first element. Solution is to use Class instead of ID:

<c:forEach items="${schedule}" var="period">
           <td>
               <div class="friends">    
                 ${period.getFriends()}
            </div>
             </td>
 </c:forEach>

 function myFunction() {
      var div = document.getElementsByClassName("friends");
      div.innerHTML = "AFJASFAS";
 }