Science Knowings: JavaScript Course For Social Media

Event Listeners

Event Listeners

Continuing from callback functions, this session will introduce you to Event Listeners, a powerful mechanism for handling user interactions and responding to events occurring on elements.

What is an Event Listener?

An Event Listener is a function that listens for and responds to specific events that occur on an element (e.g., click, hover, submit).

Element Event Listeners

You can add Event Listeners to any HTML element using the addEventListener() method. Specify the event type, listener function, and optional capture or bubbling behavior.

DOMContentLoaded Event

The DOMContentLoaded event fires when the HTML document has loaded, but before CSS and scripts are loaded and executed.

Load Event

The load event fires only after the entire page, including all resources, has loaded.

Event Handler Functions

Event Listener functions receive an Event object as a parameter, providing information about the event.

Event Object

The Event object contains properties and methods that provide detailed information about the event, such as the event type, target element, and any relevant data.

Event Bubbling & Capturing

Event bubbling and capturing allow you to determine how events are handled when they occur on nested elements.

preventDefault() & stopPropagation()

These methods allow you to prevent the default behavior of an event or stop its propagation to other elements.

Best Practices for Event Listeners

Follow best practices for using Event Listeners, such as avoiding memory leaks, using event delegation, and handling events efficiently.

Keyboard Events

Listen for keyboard input events, such as keydown, keyup, and keypress, to handle user keyboard interactions.

Mouse Events

Handle user mouse interactions with events like click, mousedown, and mousemove, providing an interactive user experience.

Form Events

Listen for events related to form elements, such as submit, change, and reset, to validate user input and process form submissions.

Custom Events

Create and dispatch your own custom events to communicate between different parts of your application or create reusable event handling components.

Next: DOM Manipulation

In the next session, we'll explore DOM Manipulation, the ability to dynamically change the HTML and CSS of a web page. Stay tuned to learn how to control and update the visual appearance of your web applications!