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DOM Node lists

The HTML DOM NodeList Object

A NodeList object is a list (collection) of nodes that are extracted from a document.

A NodeList object is similar to HTMLCollection object.

Some (older) browsers return a NodeList object instead of an HTMLCollection for methods like getElementsByClassName().

All browsers return a NodeList object for the property childNodes.

Most browsers return a NodeList object for the method querySelectorAll().

The below code selects all <p> nodes in a document:

const myNodeList = document.querySelectorAll(“p”);

The elements in the NodeList are accessed by an index number.

To access the second <p> node use the below code:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript HTML DOM</h2>

<p>Hello World!</p>

<p>Hello Norway!</p>

<p id=”demo”></p>

<script>

const myNodelist = document.querySelectorAll(“p”);

document.getElementById(“demo”).innerHTML = “The innerHTML of the second paragraph is: ” + myNodelist[1].innerHTML;

</script>

</body>

</html>

Output

JavaScript HTML DOM

Hello World!

Hello Norway!

HTML DOM Node List Length

The length property specifies the number of nodes in a node list:

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript HTML DOM</h2>

<p>Hellow World!</p>

<p>Hellow Norway!</p>

<p id=”demo”></p>

<script>

const myNodelist = document.querySelectorAll(“p”);

document.getElementById(“demo”).innerHTML = “This document contains ” + myNodelist.length + ” paragraphs.”;

</script>

</body>

</html>

Output

JavaScript HTML DOM

Hello World!

Hello Norway!

This document contains 3 paragraphs.

The length property is used to loop through the nodes in a node list.

Example

<!DOCTYPE html>

<html>

<body>

<h2>JavaScript HTML DOM</h2>

<p>Hello World!</p>

<p>Hello Norway!</p>

<p>Click the button to change the color of all p elements.</p>

<button onclick=”myFunction()”>Try it</button>

<script>

function myFunction() {

  const myNodelist = document.querySelectorAll(“p”);

  for (let i = 0; i < myNodelist.length; i++) {

    myNodelist[i].style.color = “red”;

  }

}

</script>

</body>

</html>

The Difference Between an HTMLCollection and a NodeList

A NodeList and an HTMLcollection are very much the same things.

  • Both are array-like collections (lists) of nodes (elements) extracted from a document. The nodes can be accessed by index numbers. The index starts at 0.
  • Both have a length property that returns the number of elements in the list (collection).
  • An HTMLCollection is a collection of document elements.
  • A NodeList is a collection of document nodes (element nodes, attribute nodes, and text nodes).
  • HTMLCollection items are accessed by their name, id, or index number.
  • NodeList items can only be accessed by their index number.
  • An HTMLCollection is always a live collection. Example: If you add a <li> element to a list in the DOM, the list in the HTMLCollection will also change.
  • A NodeList is most often a static collection. Example: If you add a <li> element to a list in the DOM, the list in NodeList will not change.
  • The getElementsByClassName() and getElementsByTagName() methods return a live HTMLCollection.
  • The querySelectorAll() method returns a static NodeList.
  • The childNodes property returns a live NodeList.

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