Summary

In this chapter, we’ve covered advanced event-driven programming patterns to keep a JavaScript code base performant and secure when handling large numbers of events and event listeners.

Event delegation is useful to ensure that the number of event listeners doesn’t grow with the number of DOM nodes in a client-side application where elements are inserted and removed dynamically.

Patterns for secure frame messaging mean we’re able to orchestrate iframe initialization and bidirectional communication between an iframe and its parent document.

Finally, we covered common event listener performance antipatterns to avoid the common pitfalls of event listener-heavy code bases.

Now that we’re familiar with advanced event-driven programming patterns in JavaScript, in the next chapter, we’ll cover lazy-loading and code-splitting to maximize the performance of JavaScript applications.