Intent to Deprecate and Remove: xml:base

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Philip Jägenstedt

May 13, 2015, 5:24:52 PM5/13/15
to blink-dev, Anne van Kesteren

Primary eng (and PM) emails


Remove support for xml:base entirely. This will be observable in the Node.baseURI IDL attribute for Elements as well as any code that uses baseURI() internally.


xml:base is not part of the current DOM spec, and the spec editor (Anne van Kesteren) filed a bug to remove it from Blink. This is a slight modification of the model, so that only the document has a base URL. A WIP CL shows what can be removed.

Compatibility Risk

Any content that depends on xml:base would resolve against the wrong base URL and thus fail to load some resource. The only test cases we have are for SVG <image>, so perhaps in SVG is the most likely place to find xml:base.

Alternative implementation suggestion for web developers

Use absolute URLs, change the relative URLs, or use <base href="...">.

Usage information from UseCounter

This counter was in M40, but has never registered a non-zero value, which ought to mean < 0.0001% every day. The counter is in the only code path where the xml:base attribute is read, so it covers any possible observable behavior of xml:base support.

Entry on,, or MDN

Requesting approval to remove too?

Yes, usage is already extremely low.

Chris Harrelson

May 14, 2015, 1:18:46 AM5/14/15
to Philip Jägenstedt, blink-dev, Anne van Kesteren

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Dimitri Glazkov

May 14, 2015, 10:30:48 AM5/14/15
to Chris Harrelson, Philip Jägenstedt, blink-dev, Anne van Kesteren

Jochen Eisinger

May 14, 2015, 6:03:41 PM5/14/15
to Dimitri Glazkov, Chris Harrelson, Philip Jägenstedt, blink-dev, Anne van Kesteren


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