How to lint only changed files?

lint-only-changed-files.MD

Updated on medium

find out the differences

use git diff to generate file list

git diff --name-only master

limited to certain file types

add ext filter

git diff --name-only master | grep -E "(.js$|.ts$|.tsx$)"

handle the case of file removal

ignore deleted files

git diff --name-only --diff-filter=ACMRTUXB master | grep -E "(.js$|.ts$|.tsx$)"

node scripts

add eslint to package.json

....
"scripts":
  "lint:script": "eslint -c eslintrc.js $(git diff --name-only --diff-filter=ACMRTUXB master | grep  -E \"(.js$|.ts$|.tsx$)\")"

CI script

sample with circle ci here

....
"scripts":
 "lint:script": "eslint -c eslintrc.js $(git diff --name-only --diff-filter=ACMRTUXB origin/master | grep  -E \"(.js$|.ts$|.tsx$)\")"

for stylelint

will need grep fallback for empty result cases

 
 ....
 "scripts":
   "lint:style": "stylelint --config .stylelintrc.js $(git diff --name-only --diff-filter=ACMRTUXB origin/master | grep  -E \"(.js$|.ts$|.tsx$)\" || echo \".stylelintrc.js\")"

NOTE: make sure our local branch is up to date (merge origin/master)

stylelint --config .stylelintrc.js $(git diff --name-only --diff-filter=ACMRTUXB origin/master | grep -E "(.js$|.ts$|.tsx$)" || echo ".stylelintrc.js")

There is an error. Instead " we should use ' - otherwise it doesn't work on git-bush and git-actions (ubuntu)

Script tries to fix '.stylelintrc.js' instead of skipping! Echo doesn't work in expected way on git-bush (windows OS). Any ideas?

stylelint does not support empty case

Why --diff-filter=ACMRTUXB master over --diff-filter=d --cached?

@benmosher I think that could work for local. in fact, we have switched to origin/release to make sure it is up to date

https://seeliang.medium.com/how-to-update-lint-without-lint-the-whole-project-841150aa59b0

using --relative is useful if you have a monorepo
git diff --relative --name-only --diff-filter=ACMRTUXB master

will that apply all the same?

# current branch against default (main) branch
git diff origin/main --diff-filter=ACMRTUXB --name-only -- *.js

# staged
git diff --cached --diff-filter=ACMRTUXB --name-only -- *.js 

Could you eventually include windows commands as well? Because I always get the error

grep : The term 'grep' is not recognized as the name of a cmdlet

@yinonov it depends,
origin/main is for large team that pushing to main every hour

@Anubarak not windows expert, I think you can try findstr

Why not use the --cached option for eslint?

https://eslint.org/docs/latest/user-guide/command-line-interface#caching

I check this solution and it is not better then use cache.

Just slightly adapted it for sqlfluff, another linter - and it works like a charm! thanks!