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JavaScript JavaScript and the DOM The Browser Environment Introduction to Browser Events

DOM Hierarchy - Top Levels

So I understand that the DOM hierarchy works exactly like the HTML/CSS Box model for selecting elements with JavaScript.

At the top of the tree, is the document. Is the document the entire project, or just the index.html file (or the current active page).

Are we able to select and specify documents by HTML page using the document selector. Is that the importance of understanding the DOM model and structure, to specify code for different pages and sections or our projects?


  • Create a conditional to only run on a specific page/document (although in most cases, for the web, you would just include the script in that specific page's head/footer). But maybe not so much for an app?

1 Answer

Steven Parker
Steven Parker
229,921 Points

The DOM describes the organization of each individual page of HTML code. So the "document" would be the current active page.