Add & Remove List Items In Javascript (Simple Examples)

Welcome to a quick tutorial on how to add and remove list items in Javascript. Need to dynamically update an HTML list in Javascript?

That covers the basics, but read on for more examples!

 

 

TLDR – QUICK SLIDES

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TABLE OF CONTENTS

 

 

 

1) CREATE LIST ITEM ELEMENT & APPEND

<!-- (A) HTML LIST -->
<ol id="demoA">
  <li>First</li>
  <li>Second</li>
</ol>
 
<!-- (B) JAVASCRIPT ADD -->
<script>
function addItem () {
  // (B1) CREATE NEW LIST ITEM
  var item = document.createElement("li");
  item.innerHTML = "New";

  // (B2) APPEND TO LIST
  document.getElementById("demoA").appendChild(item);
}
</script>
<input type="button" value="Add Item" onclick="addItem()">

This is the “full example” of the snippet in the introduction. Add new items to an HTML list is that simple – Just create a new list item, and append it to the list.

 

 

2) APPEND POSITION

<!-- (A) HTML LIST -->
<ol id="demoB">
  <li>First</li>
  <li>Second</li>
</ol>
 
<!-- (B) JAVASCRIPT ADD -->
<script>
function addItemPos (top) {
  // (B1) CREATE NEW LIST ITEM
  var item = document.createElement("li");
  item.innerHTML = "New";
 
  // (B2) APPEND ITEM TO TOP
  if (top) {
    document.getElementById("demoB").insertAdjacentElement("afterbegin", item);
  }
 
  // (B3) IN THE MIDDLE
  else {
    var allItems = document.querySelectorAll("#demoB li");
    var allLength = allItems.length;
    var middle = Math.ceil(allLength/2) - 1;
    if (middle<0) { middle = 0; }
    allItems[middle].insertAdjacentElement("afterend", item);
  }
}
</script>
<input type="button" value="Add Top" onclick="addItemPos(1)">
<input type="button" value="Add Middle" onclick="addItemPos()">

The previous example will always append the new list item to the bottom of the list. So how do we insert to the top or somewhere in the middle? Use insertAdjacentElement() to help you do the “precise insert”.

 

 

3) ALTERNATIVE – APPEND HTML STRING

<!-- (A) HTML LIST -->
<ol id="demoC">
  <li>First</li>
  <li>Second</li>
</ol>
 
<!-- (B) JAVASCRIPT ADD -->
<script>
function addItemHTML () {
  document.getElementById("demoC").innerHTML += "<li>New</li>";
}
</script>
<input type="button" value="Add Item" onclick="addItemHTML()">

For you guys who somehow don’t like the “object-oriented” way of creating HTML elements – We can also directly append an HTML string to the existing list.

 

4) REMOVE LIST ITEM

<!-- (A) HTML LIST -->
<ol id="demoD">
  <li>First</li>
  <li>Second</li>
  <li>Third</li>
  <li>Forth</li>
</ol>
 
<!-- (B) JAVASCRIPT REMOVE -->
<script>
function delItem (first) {
  // (B1) GET LIST + ALL ITEMS
  var list = document.getElementById("demoD");
  var allItems = document.querySelectorAll("#demoD li");

  // (B2) REMOVE FIRST ITEM
  if (first) {
    list.removeChild(allItems[0]);
  }

  // (B3) REMOVE LAST ITEM
  else {
    var last = allItems.length - 1;
    list.removeChild(allItems[last]);
  }
}
</script>
<input type="button" value="Remove First" onclick="delItem(1)">
<input type="button" value="Remove Last" onclick="delItem()">

Removing items can be a little confusing to some beginners, but the essentials are:

• Get all the list items – var all = document.querySelectorAll("#LIST li").
• var all is an HTML collection of all the list items, and it acts like an array. I.E. all[0] refers to the first item, and all[all.length - 1] refers to the last item.
• So very simply, we just remove the corresponding item from the list itself – document.getElementById("#LIST").removeChild(all[N]).

 

 

 

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EXAMPLE CODE DOWNLOAD

Click here for the source code on GitHub gist, just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

 

LINKS & REFERENCES

• Create Element – MDN
• Append Child – MDN
• Remove Child – MDN
• Insert Adjacent Element – MDN

 

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