[whatwg] Issues concerning the <base> element and xml:base

Jonas Sicking jonas at sicking.cc
Mon Aug 13 20:34:48 PDT 2007

Ian Hickson wrote:
>> Also, if we're going to be inconsistent in how current browsers and web 
>> pages handle multiple <base>s, why not simply use the first <base> for 
>> both href="" and target=""?
> Done.

I realized another limitation. It is very hard for implementations to 
'correctly' deal with dynamic modifications to bases. Ideally all 
external resources, such as <iframe>s, <img>s, css backgrounds, 
<svg:use> elements and css @imports should be updated to potentially use 
new URIs. This can happen when <base> elements and xml:base attributes 
are inserted or mutated. So far no UA that I know of does this, and it 
would be very hard to implement.

What I suggest is that we add similar language as the XBL spec does for 
xmlns attributes and xbl:attr attributes. Say that dynamic modifications 
are allowed, but that the implementation is not expected to update the 
resolved URI unless the URI is explicitly touched.

> This might be something we'll have to revisit near the end of the HTML5 
> development cycle, to see where the Web content has settled and to see 
> what browser vendors feel is required to support Web content.

I'm ok with this.

/ Jonas

More information about the whatwg mailing list