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!
![Chris Coyier’s Favorite CodePen Demos]()
David asked me if I'd be up for a guest post picking out some of my favorite Pens from CodePen. A daunting task! There are so many! I managed to pick a few though that have blown me away over the past few months. If you...
![Introducing MooTools Templated]()
One major problem with creating UI components with the MooTools JavaScript framework is that there isn't a great way of allowing customization of template and ease of node creation. As of today, there are two ways of creating:
new Element Madness
The first way to create UI-driven...
![Advanced CSS Printing – Using JavaScript Double-Click To Remove Unwanted DIVs]()
Like any good programmer, I'm constantly searching around the internet for ideas and articles that can help me improve my code. There are thousands of talented programmers out there so I stumble upon some great articles and code snippets that I like to print out...
![Using Opacity to Show Focus with jQuery]()
A few days back I debuted a sweet article that made use of MooTools JavaScript and opacity to show focus on a specified element. Here's how to accomplish that feat using jQuery.
The jQuery JavaScript
There you have it. Opacity is a very simple but effective...
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.