Using JavaScript off-DOM is an efficient way to manipulate web page content. By “work off-DOM,” I mean “work inside of the browser memory instead of on a web page.”

A simple web search will display lots of good reasons for doing off-DOM JS. In my case, I was working on a personal project where it looked like I would need to do it so I could set my page up in a specific way. I may not need to do this anymore but still gained knowledge on doing off-DOM JavaScript and want to share what I learned.

The spark for my learning this stuff was Paul Irish’s excellent screencast, “HTML5, CSS3, and DOM Performance”, recorded a little over a year ago from this post. I also read a ton of articles and blog posts on the subject and, of course, wrote some code to test things out. I share all this stuff in this three-part screencast tutorial.

I do the following in this screencast:

  • create a document fragment off-DOM with createDocumentFragment().
  • create a bunch of web page elements off-DOM with createElement() and createTextNode().
  • arrange them the way I want to arrange them with appendChild(), innerHTML and the jQuery .attr() method.
  • load them into a document fragment with appendChild().
  • load the document fragment onto the web page with, yet again, appendChild().
  • duplicate the content that was just loaded on the page with cloneNode().
  • adjust the duplicate content with the JavaScript stuff just discussed as well as childNodes[].
  • load the duplicate content onto a web page with, one more time, appendChild().

While certain aspects of this tutorial are for the beginner, I am assuming that you understand JavaScript variables and arrays…arrays especially. Please read up on them over at MDN if you don’t…variables link here, arrays link here.

And, of course, the tutorial’s final code on GitHub is here.


Part 1

Part 2

Part 3