7.4 Optimizing Database Structure - (Private Browsing) Using Javascript « WordPress Codex - (Private Browsing) Using Javascript JavaScript will work within WordPress.
It can be used within WordPress template files in WordPress Themes or Child Themes. JavaScript cannot be added to post content without a special WordPress Plugin that removes the filters that prevent unwanted code within the post content area, for the protection of the user. AJAX « WordPress Codex - (Private Browsing) What is Ajax?
Ajax (Asynchronous JavaScript And XML) is a technology that allows a web page to perform actions or update dynamically, without completely reloading. The idea is that by using Ajax technology, a web site can be more responsive and interactive than a non-Ajax site. For instance, without Ajax, Google Maps might require you to click a link on the left side of the map and wait for the page to reload in order to scroll the map to the left. With Ajax, you can instead simply drag the map to scroll, and while there might be a small delay, it is a much shorter delay and less disruptive process than if you had to wait for the entire page to load.