IFRAME contentWindow is null
I like clean code so I do what I can to avoid unwanted JavaScript global variables. I initially thought that keys(window) would give me window property leaks but that didn't work because browsers returned different results, so I moved on to using an IFRAME to compare default window property keys.
When I first tried this method, I got a lame error about an IFRAME element's contentWindow property being null. Ugh. It didn't take long to figure out why: you need to wait until the IFRAME has loaded to get the contentWindow:
var iframe = document.createElement('iframe');
iframe.onload = function() {
// contentWindow is set!
};
iframe.src = 'about:blank';
document.body.appendChild(iframe);
Of course you'll want to add the onload event before setting the src. If you use the load event to check for the contentWindow property, you'll be in business!
![Animated 3D Flipping Menu with CSS]()
CSS animations aren't just for basic fades or sliding elements anymore -- CSS animations are capable of much more. I've showed you how you can create an exploding logo (applied with JavaScript, but all animation is CSS), an animated Photo Stack, a sweet...
![Write Simple, Elegant and Maintainable Media Queries with Sass]()
I spent a few months experimenting with different approaches for writing simple, elegant and maintainable media queries with Sass. Each solution had something that I really liked, but I couldn't find one that covered everything I needed to do, so I ventured into creating my...
![MooTools HTML Police: dwMarkupMarine]()
We've all inherited rubbish websites from webmasters that couldn't master valid HTML. You know the horrid markup: paragraph tags with align attributes and body tags with background attributes. It's almost a sin what they do. That's where dwMarkupMarine comes in.
![Drag. Drop. Lock.]()
I've received dozens of emails about my Six Degrees of Kevin Bacon Using MooTools article. The MooTools in my article contained a lot of conditional code to require correct dropping per the game and many people requested that I simplify the process and just...
Don’t you need to append your iframe element to a DOM tree so that the browser fetches its target content ? I mean, I know that old IE will load scripts as you parse an “HTML string” but in modern browsers, I thought that the asset does not get loaded until you append the element to a document (and in my opinion this it what makes constructors such as
Image()so useful).Yes, good catch! Updated!
Unfortunately this does not appear to be 100% reliable in chrome (i’m currently using version 62.0.3202.94, but this appears to have been an issue for a while), as sometimes contentWindow can still be null when onload is triggered.
This solution worked for me! Thanks a lot!
Thank you, saved me hours!
Sharry