Traversing the DOM in JavaScript

Introduction

To traverse the DOM, the access always starts from the document.

The root: documentElement and body

The root of the DOM is always document.documentElement.

This special property will provide access to the topmost HTML tag.

Another starting point can be the document.body, which represents the BODY tag.

Both entry points are valid. But document.body can be null.

For example, we access document.body from an inline script in the HEAD, prepare to see null instead. That’s natural, because there is no BODY yet.

On the contrary, document.documentElement is always available.

document.body can’t be undefined.

In the world of the DOM, an “element not found” or “no such element” is always null.

Child elements

childNodes

An element keeps references to children in childNodes array-like property.

Children

Sometimes we need to browse only element nodes, skipping text nodes. For this we use children.

It contains all element nodes.