feat(v2): auto-generated sidebars, frontmatter-less sites

[slorber]

Motivation

Fixes #3464

Good description of this PR here: #3464 (comment)

• Make it easy to create a site without any sidebar, and infer the sidebar from the FS structure
• Make it easy to have no frontmatter at all, and derive good metadata from FS naming conventions (file number prefixes)

Breaking changes:

• A site without sidebars file will now autogenerate a sidebar automatically from the docs folder. Use an empty sidebars file if you want no sidebar at all.
• By default, we strip numbers in front of folders/filenames, as numbers prefixes are often used to provide docs order: this could have unintended side-effects if you have existing docs starting with numbers.

Have you read the Contributing Guidelines on pull requests?

yes

Test Plan

tests, preview, dogfooding

[netlify]

[V1]

Built with commit f23e823

https://deploy-preview-4582--docusaurus-1.netlify.app

[github-actions]

Size Change: +33 B (0%)

Total Size: 598 kB

Filename	Size	Change
website/build/assets/js/main.********.js	422 kB	+33 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
website/build/assets/css/styles.********.css	87.2 kB	0 B
website/build/blog/2017/12/14/introducing-docusaurus/index.html	62.1 kB	0 B
website/build/docs/introduction/index.html	235 B	0 B
website/build/index.html	26.9 kB	0 B

_{compressed-size-action}

[netlify]

[V2]

Built with commit f23e823

https://deploy-preview-4582--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🟠 Performance	85
🟢 Accessibility	96
🟢 Best practices	100
🟢 SEO	100
🟢 PWA	95

Lighthouse ran on https://deploy-preview-4582--docusaurus-2.netlify.app/

[ywjr]

Generating sidebar automatically is a good function. I suggest that when generating sidebar automatically, the system can add filtering rules to filter out some files (such as readme. md

[borekb]

By default, we strip numbers in front of folders/filenames, as numbers prefixes are often used to provide docs order: this could have unintended side-effects if you have existing docs starting with numbers.

(emphasis mine) @slorber That is very true for us 😄. We have a numbered tutorial like this:

• 01-intro
• 02-build-ui
• 03-fetch-data
• etc.

The files keep working as 01-intro.md but URLs are suddenly without these numbers, leading to 404s 🙁.

Any way to work around this?

[slorber]

@borekb not sure to understand why you want the numbers in the URLs?

In any case, you should be able to use a custom slug to add these numbers back, or simply disable the feature with numberPrefixParser: false in the docs plugin/preset config

[borekb]

It's just how it was, the tutorial part of our docs site used numbers in the URLs. Thanks for the tip with numberPrefixParser!

[0Grit]

@slorber Assuming based on this that I won't be able to do what I asked about in an earlier comment?
#3464 (comment)

[slorber]

No I don't think it's possible atm but we may add support for it if there's a good use-case exposed clearly, preferably with a concrete example showcasing the problem (seeing sources is better)