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!
![How I Stopped WordPress Comment Spam]()
I love almost every part of being a tech blogger: learning, preaching, bantering, researching. The one part about blogging that I absolutely loathe: dealing with SPAM comments. For the past two years, my blog has registered 8,000+ SPAM comments per day. PER DAY. Bloating my database...
![Create a CSS Flipping Animation]()
CSS animations are a lot of fun; the beauty of them is that through many simple properties, you can create anything from an elegant fade in to a WTF-Pixar-would-be-proud effect. One CSS effect somewhere in between is the CSS flip effect, whereby there's...
![Create a Dojo-Powered WordPress Website View]()
Yesterday I showed you WordPress' awesome JSON plugin named JSON API. Now that I can get my blog posts in JSON format, it's time to create an awesome AJAX'ed web app with that data. I've chosen to use the power of Dojo and Dijit to...
![Duplicate DeSandro’s CSS Effect]()
I recently stumbled upon David DeSandro's website when I saw a tweet stating that someone had stolen/hotlinked his website design and code, and he decided to do the only logical thing to retaliate: use some simple JavaScript goodness to inject unicorns into their page.
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.