[whatwg] clarification for data-uris in window.open and SOP

Ian Hickson ian at hixie.ch
Wed May 11 15:56:57 PDT 2011

On Tue, 8 Feb 2011, Andreas Göbel wrote:
> Recently I needed to have some base64 encoded images to show in a new 
> window. My first attempt was, to just pass the 
> data:image/png;base64,<data> string as first argument from 
> window.open().
> This works in all browsers that support data-uris, but it is terribly 
> slowing down the browser when passing in images with a "big" filesize. 

In new UAs, a possibly better solution is to do a window.open() of the URL 
obtained from URL.createBlobURL() using a Blob containing the image 
(assuming you have a blob version of the image somehow -- not sure how you 
got the base64 contents).

> My idea was to do something like this:
> var largeprev = window.open('data:text/html;charset=utf-8,' + escape('<div/>'), 'large'),
>     that      = this;
>     largeprev.addEventListener('DOMContentLoaded', function(e) {
>         largeprev.alert('loaded');
>         largeprev.document.querySelectorAll('div')[0].appendChild(that);
>     }, false);
> this works great in Firefox (3.6.x), but Chrome and Safari treat the 
> returned DOMWindow object like it represents a foreign domain. 

Yeah, that's a known bug in WebKit that they plan to fix one day but that 
is hard to fix.

You can just open 'about:blank' in the meantime, it has much the same 

   var win = window.open('about:blank');

...or some such.

On Wed, 9 Feb 2011, Andreas Göbel wrote:
> Well it's not an option for me to use a browser setting / commandline 
> argument to make this work. The only way I'm aware of is to use 
> document.write() like
>         var virtualdom = '<html><body><img src="' + 'data:image/png;base64,R0lDWRW...' + '"/></body></html>',
>             prev       = window.open('', 'large');
>         prev.document.open();
>         prev.document.write(virtualdom);
>         prev.document.close();
> in order to make this work.

That would work too, yes. ('' is the same as 'about:blank' here.)

On Tue, 8 Feb 2011, Mihai Parparita wrote:
> I believe you're running into http://crbug.com/58999

That's the one.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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