DOM selection and manipulation in jQuery is essential for identifying web page components. Event handling facilitates interaction with these identified components by the end users by responding to their input devices.

Touch screens have turned the user’s fingers into input devices and events such as those responding to gestures are handled specifically with jQueryMobile—a framework for creating mobile applications. APEX applications don’t need to include the mobile framework to handle standard tap and scrolling events. A small library called Touch Punch can be included on a web page to make it respond to dragging gestures, useful for slider items.

Mastering the concept of selectors is a difficult part of learning jQuery. There are a number of methods to identify the right page element to act upon. In addition to the selectors mentioned in this blog, jQuery also provides the ability to traverse up and down the HTML tree using specific functions.

More detailed examples of selectors will be introduced as the blog details traversal methods in addition to other fundamental concepts and common features. Just like SQL, a good percentage of what you’ll ever need to do will already have an appropriate documented function.

jQuery has been included by default in Oracle APEX applications since the advent of dynamic actions. The application builder provided wizards to define event handlers that interact with page components.

In addition to dynamic actions, Oracle APEX provides the ability to utilize other jQuery features declaratively. For instance, date pickers and autocomplete items use the jQuery framework. Many types of APEX plug-ins also use the jQuery library to function.

Before diving deeply into how the selector works, let’s look at how the web page is structured, see some basic syntax examples, and explore the SQL analogy.

Fundamentally, it comes back to CSS selectors identifying page elements. Sizzle.js is the engine that powers the jQuery library, and it extends the number of selectors available to provide more granular access to elements on the page. jQuery extends this further by traversing the tree that represents the web page, and visiting and acting upon a set of specified elements.