Remove dist files from top-level tsconfig to speed up eslint checks 🏎🚀

[bajtos]

This speeds up npm run eslint from about 4m10s down to 2m50s.

More importantly, it enables proper caching behavior, so that subsequent runs of npm run eslint are super quick, even after npm run build modified dist files.

$ npm run build
(...)
$ time npm run eslint

> loopback-next@0.1.0 eslint /Users/bajtos/src/loopback/next
> node packages/build/bin/run-eslint --report-unused-disable-directives --cache .


real	0m1.626s
user	0m1.143s
sys	0m0.393s

(That's less than 2 seconds for subsequent eslint runs leveraging the cached data!)

See the discussion in #4382 for more context.

Checklist

👉 Read and sign the CLA (Contributor License Agreement) 👈

• npm test passes on your machine
• New tests added or existing tests modified to cover all changes
• Code conforms with the style guide
• API Documentation in code was updated
• Documentation in /docs/site was updated
• Affected artifact templates in packages/cli were updated
• Affected example projects in examples/* were updated

👉 Check out how to submit a PR 👈

[derdeka]

Great discovery!

[derdeka]

Suggested change

	"extensions/*/node_modules/**",
	"**/node_modules/**",

BTW, any idea why this is not **/node_modules/**, ?

[bajtos]

IDK, to be honest. I was thinking about simplifying the pattern too, but then decided to keep my changes minimal to get them landed faster.

Would you like to open a follow-up pull request to simplify this part of exclude configuration?

[raymondfeng]

@bajtos Interesting. Does it hint that the patterns in https://github.com/strongloop/loopback-next/blob/master/.eslintignore have some issues?

[bajtos]

Does it hint that the patterns in https://github.com/strongloop/loopback-next/blob/master/.eslintignore have some issues?

As far as I understand from reading the discussion in typescript-eslint/typescript-eslint#389, .eslintignore is applied by eslint only. typescript-eslint adds TypeScript to the mix, at which point tsconfig.json is consulted independently of .eslintignore. So it's important to exclude build artifacts in both files.

Quoting from typescript-eslint/typescript-eslint#389 (comment):

if you came here because your tslint/typescript setup is slow, I recommend you to try the following:

1. Setup an .eslintignore file to ignore node_modules as well as build / non-typescript files
2. Do the same thing for tsconfig.json via the "exclude" property to exclude node_modules or non typescript files.

[raymondfeng]

Should we fix https://github.com/strongloop/loopback-next/blob/master/packages/cli/generators/project/templates/tsconfig.json.ejs#L33-L36 too?

[bajtos]

@bajtos Interesting. Does it hint that the patterns in https://github.com/strongloop/loopback-next/blob/master/.eslintignore have some issues?

To actually answer your question, I believe the patterns in .eslintignore are fine, nothing to fix there.

[dougal83]

Give that man a raise! :) Still a little shocked, had to run it three times to be sure!

[raymondfeng]

Did you remove .eslintcache file before npm run eslint for the benchmark?

[bajtos]

Did you remove .eslintcache file before npm run eslint for the benchmark?

No. First I run npm run lint to update the cache, that took several minutes (more or less the same time as before my changes). Then I run npm run build and measured how long it takes to run npm run lint.

[bajtos]

I am going to land this pull request as it is now, since it has been approved by many reviewers and there are no objections ("request changes" reviews).

Things we can fix in follow-up pull requests:

• fix https://github.com/strongloop/loopback-next/blob/master/packages/cli/generators/project/templates/tsconfig.json.ejs#L33-L36 too?
• use pattern **/node_modules/** - see Remove dist files from top-level tsconfig to speed up eslint checks 🏎🚀 #4707 (comment)