How to Implement Lazy Loading for Images in Websites

Welcome to the magical world of web development, where we conjure complex websites with mere strokes of our keyboard (and maybe an incantation or two). And today, my fellow wizards-in-training, we are going to decode a spell known as ‘Lazy Loading’.
Before we start, let’s break the ice! Here’s a riddle for you: What do a procrastinator and an image on a website under the spell of lazy loading have in common? Answer: Neither of them gets to work until the very last moment.
Alright, enough with the jesting. On to the serious stuff!

What on Earth is Lazy Loading?

Lazy loading is a design pattern that defers the loading of non-critical resources at page load-time. Instead, these resources are loaded when they are required. With images, for instance, they are loaded only when a user scrolls down to them. It’s evident how this technique can significantly increase page speed, especially when there are numerous large images or a gallery.
Now that you’re fascinated, let’s get our hands dirty!

Implementing Lazy Loading for Images in HTML

To get started with lazy loading, we first need to mark a specific image for lazy loading in HTML code. Doing this is simpler than tricking a troll into giving up his gold. All we need to do is add the following line inside our img tag:
<code>loading="lazy"
Did I hear a gasp of disbelief? Yes, my friend, it really is that simple!

Deep Dive into Lazy Loading with JavaScript.

If you’re a confident coder looking for a challenge (and I bet you are), JavaScript provides a more advanced approach. Enter the Intersection Observer API!
Would you like to hear something incredible? The Intersection Observer API lets you know when an observed element intersects either the device’s viewport or a specified element. It’s playing a game with you: ‘I spy with my little eye…something intersecting with something.’

Setting Up Intersection Observer API

To implement lazy loading with Intersection Observer, the primary steps involve creating a new Intersection Observer object and providing it with a callback function and specific options.
Inside the callback function, we check if the target element is intersecting with the viewport (or other specified elements). If it is, we then load the image, changing the image source to the actual image.
This approach gives you the power to customize and determine specifically when and under what conditions your images load.
And there you have it! You have just mastered a new spell in your web development spellbook.
Remember, practice makes perfect. So, keep experimenting with different loaders, thresholds, and options. Also, do not forget that each website is a unique ecosystem, and some techniques may perform better than others.
And by the way, next time when someone accuses you of being lazy, you can tell them you are simply ‘Lazy Loading to enhance performance.’ Happy coding!