Make the 404 page useful

[ddbeck]

Summary

Some pages 404 for good, but unexplained reasons. The 404 page should help MDN readers find the content they're looking for with a prominent search box, links to mdn/archived-content, Firefox Source Docs, the Wayback Machine, or to raise an issue on mdn/content.

Making the 404 page useful

Over the years, lots of content has been removed from MDN, for many reasons including:

• It moved elsewhere (e.g., https://firefox-source-docs.mozilla.org/)
• It was archived (i.e., put in https://github.com/mdn/archived-content)
• It was deleted (e.g., irrelevant content)

Some of these removals have been supported by useful redirects. However, in many cases, there's no sensible redirect because there's no plausible replacement content on or off MDN, or the removal was simply mismanaged. In those cases, we should provide a 404 page that actually helps readers find the content they're looking for.

The 404 page could help by linking mdn/archived-content, Firefox Source Docs, the Wayback Machine, or to the form to create a new issue on mdn/content. Ideally, the last option would only apply when the document referrer is on MDN itself.

Related issues

Inspired by this comment from @Gitoffthelawn: #5484 (comment)

[OnkarRuikar]

We can at least give directions where to find these pages.
For example like the google search:

We can have the suggestion list like:

• Try searching the term in search box, the page may have moved to a new location on the same site.
• Try on Wayback Machine: https://web.archive.org/web/*/https://developer.mozilla.org/en-US/docs/Learn (here we show preconstructed URL).
• Try something something.
• ....

And some cool Mozilla dinosaur art would be nice:

*Taken from one of the community website page.

[Gitoffthelawn]

@OnkarRuikar

Those are all great ideas!

For your first point, I think also directing the user to use terms that may yield good results. Or, even better, add search keywords to specific pages that may benefit from such additions.

BTW, your Wayback Machine trick of using an asterisk is quite clever and useful. Is that trick (and perhaps similar ones) documented somewhere?

[OnkarRuikar]

Or, even better, add search keywords to specific pages that may benefit from such additions.

We already have tags on all pages in front-matter section. I think they can be used. We need to check how the current search feature works.

BTW, your Wayback Machine trick of using an asterisk is quite clever and useful. Is that trick (and perhaps similar ones) documented somewhere?

Thanks! It is documented here.
For your ready reference here is the relevant part:

Pay attention to the date code embedded in the archived url. This is the list of numbers in the middle;
it translates as yyyymmddhhmmss.
For example in this url http://web.archive.org/web/20000229123340/http://www.yahoo.com/ the date the site was crawled was Feb 29, 2000 at 12:33 and 40 seconds.

You can see a listing of the dates of the specific URL by replacing the date code with an asterisk (*), ie: http://web.archive.org/*/www.yoursite.com

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@schalkneethling what do you think about #5973 (comment)?
If we are ready to have this feature then may I start working on it?

As this issue page is receiving new comments it is not "idle" anymore. Can we update the workflow to remove idle status. Because if there is auto close set on idle issues after certain days. Then this may get closed.

[schalkneethling]

Closing in favor of the following discussion: mdn/mdn-community#125 - Please continue sharing your ideas, everyone. Thanks!