feature request: --cache similar to ESLint for remark-cli?

[Trott]

Subject of the issue

It would be useful for Node.js core if remark-cli had a --cache option similar to that used in ESLint. We fake it right now in our Makefile by generating a timestamp file and only linting if the directory of markdown files was modified after the timestamp file. This works OK in most situations but has the following disadvantages:

• If only one file changes, it re-lints the entire directory instead of just the file that changed.
• If our rules change, it's not smart enough to know that it needs to re-lint everything. (ESLint knows that its cache is invalid if the config settings are changed.)
• If remark-cli itself is updated, the Makefile does not know to re-lint everything. (Again, ESLint knows that its cache is invalid if the cache was generated by a different version of ESLint.)

Your environment

• macOS 10.13.5
• remark-cli, remark-preset-lint-node
• node 10.4.1, npm 6.1.0

Steps to reproduce

We use something like remark-cli/cli.js -q -f doc where doc is a directory with a lot of markdown files. Ideally, it would be great if we could pass --cache to generate a .remarklintcache file the way ESLint generates an .eslintcache file.

Expected behaviour

With the cache file, running the command again and again should be much faster (unless all the files change, a rule is changed, or the version of remark-cli is updated).

Actual behaviour

Well, the feature isn't implemented so I get the remark-cli help message.

[Murderlon]

I will give this a shot this weekend :)
Also, this feature will live in the underlying unified-engine, the already existing issue can be found here 👉 unifiedjs/unified-engine#22

[Murderlon]

Turns out I'm completely packed till I leave for vacation in two weeks so I won't be able to do this for at least a month. To not claim a stale contribution, consider me out until I say here otherwise. So if anyone is excited to pick this up you don't have to hesitate :)