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!
![From Webcam to Animated GIF: the Secret Behind chat.meatspac.es!]()
My team mate Edna Piranha is not only an awesome hacker; she's also a fantastic philosopher! Communication and online interactions is a subject that has kept her mind busy for a long time, and it has also resulted in a bunch of interesting experimental projects...
![Responsive and Infinitely Scalable JS Animations]()
Back in late 2012 it was not easy to find open source projects using requestAnimationFrame()
- this is the hook that allows Javascript code to synchronize with a web browser's native paint loop. Animations using this method can run at 60 fps and deliver fantastic...
![Create GitHub-Style Buttons with CSS and jQuery, MooTools, or Dojo JavaScript]()
I'm what you would consider a bit of a GitHub fanboy. We all know that GitHub is the perfect place to store repositories of open source code, but I think my love of GitHub goes beyond that. GitHub seems to understand that most...
![Animated AJAX Record Deletion Using jQuery]()
I'm a huge fan of WordPress' method of individual article deletion. You click the delete link, the menu item animates red, and the item disappears. Here's how to achieve that functionality with jQuery JavaScript.
The PHP - Content & Header
The following snippet goes at the...
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