Why Does \'this\' Behave Differently in Arrow Functions Within Event Handlers?

Arrow Functions and "this" Binding in Event Handlers

When working with JavaScript's ES6 arrow functions, developers may encounter unexpected behavior when relying on the "this" keyword within event handlers. Unlike traditional function expressions, arrow functions inherit their this context from their surrounding scope, not from the context in which they are called.

The Problem: undefined $(this)

In the provided code snippet, the arrow function approach binds "this" to the global context (window object) instead of the intended element attached to the event listener. As a result, $(this) returns undefined because there is no corresponding jQuery object within the global context.

Solution: Use event.currentTarget

To resolve this issue and obtain the correct element reference, it is recommended to use event.currentTarget within the event handler. Unlike "this," event.currentTarget always refers to the DOM element currently being handled by event listeners.

Example using event.currentTarget

Here is the modified code snippet with the event.currentTarget fix:

<code class="javascript">dom.videoLinks.click((e) => {
            e.preventDefault();
            console.log($(e.currentTarget));
            var self = $(e.currentTarget),
                url = self.attr(configuration.attribute);

            eventHandlers.showVideo(url);

            // Deactivate any active video thumbs
            dom.videoLinks.filter('.video-selected').removeClass('video-selected');

            // Activate selected video thumb
            self.addClass('video-selected');
        });</code>

.currentTarget vs .target

To understand event handling better, it is important to note the difference between event.currentTarget and event.target.

• event.currentTarget: Represents the element to which the event listener is attached.
• event.target: Represents the element that initially triggered the event.

In the context of event bubbling, event.currentTarget remains the same throughout the propagation process, while event.target changes according to the element that is currently handling the event.

Conclusion

Arrow functions provide concise syntax in JavaScript, but it is crucial to remember their unique scoping behavior when working with "this" within event handlers. By leveraging event.currentTarget, developers can consistently access the appropriate DOM element and effectively handle events in their JavaScript applications.

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