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Comment by xymostech | Hacker News Reader

Does anyone know why about:blank is so magical that can't use the new HTML parser? Can it not be parsed like other pages?

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Here's Henri Sivonen (the author of the HTML5 parser that is now Firefox' sole parser) on the subject: http://hsivonen.iki.fi/about-blank/.

From a quick reading, it seems to be a mix of synchronous vs asynchronous parsing, historical reasons, and stuff. He identifies eight different behaviors.

The Joy of about:blank: http://hsivonen.iki.fi/about-blank/

Thanks for the link unwind/paulrouget2.

I think it went a little over my head. What role does about:blank actually play? I'm assuming that the wild behaviour and parsing difficulty is the result of it performing some special function (beyond just returning a blank page).

A browsing context doesn't start its life empty. Instead, when a browsing context is created, if a JS program looks at what's in there, there's an about:blank doc in there. Since you can create a browsing context synchronously (e.g. document.body.appendChild(document.createElement("iframe"))), there has to be a way for the initial about:blank document to materialize synchronously. The HTML parser is always async. (Edit: The HTML parser is always async when loading a URL. Then there are innerHTML, createContextualFragment and DOMParser, which are synchronous.)

Add various events (readystatechange, DOMContentLoaded, load) to added fun. And the fact that browsing contexts that are top-level from the Web perspective are iframe-like from the XUL perspective and the code for dealing with this duality is a mess.

Really this seems incredibly strange.

Typical Mozilla nonsense

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