Event Loop Blocking + Lazy images

👉 Overview

👀 What ?

Event Loop Blocking and Lazy Images are two essential aspects of web development and optimization. Event Loop Blocking refers to a situation where a long-running operation prevents the execution of other codes in JavaScript. Lazy Images, on the other hand, is a technique used to defer loading off-screen images until the user scrolls to them, improving performance and reducing data usage.

🧐 Why ?

Understanding Event Loop Blocking is crucial because it can significantly affect the performance of your JavaScript code. If a task takes too long to execute, it can block other tasks in the queue, leading to a sluggish or unresponsive interface. Similarly, Lazy Images is a vital technique for improving website performance. Loading images only when needed reduces initial page load time, minimizes user bandwidth usage and improves user experience.

⛏️ How ?

To avoid Event Loop Blocking, you can use asynchronous programming concepts like promises and async/await in JavaScript. For Lazy Images, you can use Intersection Observer API or simply add loading='lazy' attribute to your img tag in modern browsers. It's vital to test these implementations for compatibility and fallback for older browsers.

⏳ When ?

Event Loop Blocking and Lazy Images techniques have become increasingly important with the rise of complex web applications and growing user expectations for performance. They are commonly used in today's web development practices.

⚙️ Technical Explanations

Event Loop in JavaScript handles the execution of multiple tasks and ensures they run one after the other. When one task takes too long, it blocks the rest, leading to performance issues. This is known as Event Loop Blocking. The solution lies in asynchronous programming where JavaScript's non-blocking I/O model allows other tasks to run without waiting for the blocking task to finish.\n\nLazy Images, on the other hand, leverage the browser's ability to defer loading images until they're needed. This can be achieved through the Intersection Observer API, which watches changes in the intersection of elements with a parent element or the viewport. When the image comes into the viewport, it's loaded, thus saving resources.