Lazy Load IFRAMEs
We've known for a decade that lazy loading resources like JavaScript, CSS, and especially images is a massive performance win for web pages. At first we used tricks and JavaScript to do the lazy loading, but more recently native image lazy loading has debuted in browsers.
Did you know that you can also lazy load IFRAMEs using the same loading="lazy" attribute and value?
<iframe
src="https://davidwalsh.name/"
loading="lazy"
onload="alert('Loaded!');"
/>
You can see how lazy loading IFRAMEs works with this demo:
This single attribute to perform a complex but useful operation is the ideal solution for lazy loading just about anything. I'm so thankful that browsers are implementing APIs that make using best practices so easy!
![Write Better JavaScript with Promises]()
You've probably heard the talk around the water cooler about how promises are the future. All of the cool kids are using them, but you don't see what makes them so special. Can't you just use a callback? What's the big deal? In this article, we'll...
![Creating Scrolling Parallax Effects with CSS]()
Introduction
For quite a long time now websites with the so called "parallax" effect have been really popular.
In case you have not heard of this effect, it basically includes different layers of images that are moving in different directions or with different speed. This leads to a...
![9 Mind-Blowing Canvas Demos]()
The <canvas> element has been a revelation for the visual experts among our ranks. Canvas provides the means for incredible and efficient animations with the added bonus of no Flash; these developers can flash their awesome JavaScript skills instead. Here are nine unbelievable canvas demos that...
![jQuery Random Link Color Animations]()
We all know that we can set a link's :hover color, but what if we want to add a bit more dynamism and flair? jQuery allows you to not only animate to a specified color, but also allows you to animate to a random color.
The...
This browser feature looks really like a huge gamechanger. Would love so much to use it with profit although it doesn’t seem to work correctly for me.
[First of all, using it with images instead of iframes always worked perfectly, so all this regards only loading=”lazy” for iframes.]
After hours of testing on different pages, what I see is that using loading=”lazy”, Iframes load WAY TOO EARLY.
This apparently buggy behavior happens only if the page itself is NOT loaded from another iframe. So this rules out CodePen as a viable tool to show this.
Let’s make a text.html file from this code, almost identical to your example, to highlight exactly what I’m saying:
https://gist.github.com/jeff-at-livecanvas/bb1a803465419c62d623305daf6722cd
Opening this file in a Chrome window, with an internal height of 700 pixels, shows the Loaded! message immediately.
Same happens with latest Firefox too.
Would be great if somebody could shed some light on this.