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!
![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...
![An Interview with Eric Meyer]()
Your early CSS books were instrumental in pushing my love for front end technologies. What was it about CSS that you fell in love with and drove you to write about it?
At first blush, it was the simplicity of it as compared to the table-and-spacer...
![Editable Content Using MooTools 1.2, PHP, and MySQL]()
Everybody and their aerobics instructor wants to be able to edit their own website these days. And why wouldn't they? I mean, they have a $500 budget, no HTML/CSS experience, and extraordinary expectations. Enough ranting though. Having a website that allows for...
![Add Styles to Console Statements]()
I was recently checking out Google Plus because they implement some awesome effects. I opened the console and same the following message:
WARNING!
Using this console may allow attackers to impersonate you and steal your information using an attack called Self-XSS.
Do not enter or paste code that you...
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