Has this ever worked? Was this recently broken?

According to the W3 wiki:
http://www.w3.org/wiki/HTML/Elements/isindex
"No, really, don't use it. This element is deprecated. It is not implemented anymore."

Here's where we discussed removing this:

https://groups.google.com/a/chromium.org/d/msg/blink-dev/14q_I06gwg8/0a3JI0kjbC0J

Sorry. The consensus was that ISINDEX should be removed, despite that breaking some sites.

@erikchen: This used to work, it was removed; see eg https://codereview.chromium.org/96653004/

This is a troubling precedent. Is there a single other 'early HTML' feature which has been similarly dropped? Will FONT be deleted too some day? These features are important for accessing historical websites.

Note that Chrome is willfully violating the HTML parsing algorithm here, which states that any ISINDEX tag should be replaced with an equivalent FORM.

I believe we considered these kinds of issues in the thread Dominic linked above.

I don't believe a slippery-slope is something to worry about in this specific case, as the rationale for removing `<isindex>` was based on security-relevant modifications to the parser. `<font>` doesn't have those same concerns; in fact, no other HTML element has those concerns. Removing `<isindex>` allowed us to remove the "pretend that this token is actually this other series of tokens" machinery from the parser entirely.

Please put <isindex> back.  If the way you were implementing it (a fake form) was broken then implement it differently.  You're just making your life easier at the expense of people who have old scripts who will have to rewrite them -i.e ME.

Ditto that. We now have three URLs which people have been using for a long time (since the 1990s) which have, in the eyes of non-technical users, become mysteriously broken. I have been using the words.exe online interface linked in the original issue since 2008, when I started learning the language (at that time, I didn't even know what <ISINDEX> was). marc.men...@gmail.com pointed recently in that threat to two other pages, also around since the 90s, which he has also presumably depended on since then.

Let me ask this: has there *ever* been a single security vulnerability in Blink related to how the HTML parser handles <ISINDEX>? Or in any other browser? The WHATWG specified <ISINDEX> as a special case of <FORM> specifically to make its implementation easier while remaining compatible and secure, as I understand it.

I realize that my argument was a slippery-slope, and your response did little to satisfy my concerns. In the future, will it be: "removing <FONT> allowed us to remove the 'pretend this element without CSS attributes actually has styling' machinery from the renderer entirely"?

This has caused a serious dent in the trustability of the Web as a long-term platform. I will note that every single WHATWG person who participated in the threat said this was a bad idea.