We start out with a conditional check. Remember that pageNum is the number of the next page, so if it is greater than max, there are no more pages to load. In that case, we don’t want to add the button.
If there is new content to load though, then we look for the #content div, and add two things to the end of it. The first is an empty div, which we will later use to insert our posts into.
The second is the button itself (A regular HTML link), wrapped up in a paragraph.
Finally, we look for the .navigation div and remove it. If your theme uses a different class for the navigation buttons, you will need to change that (.navigation is the default that the 2010 theme uses). The same thing applies to the #content div too!
The result of the code above is that our button is now in place, though it won’t do anything yet.
And because we did it all with JavaScript, we know our plugin degrades gracefully (Because if the JavaScript isn’t loaded, no changes will be made to the page).
Now, let’s take care of what happens when the user actually clicks the button.