Pre-commit hook for eslint, linting *only* staged changes.

pre-commit.sh

#!/bin/bash

for file in $(git diff --cached --name-only | grep -E '\.(js|jsx)$')
do
  git show ":$file" | node_modules/.bin/eslint --stdin --stdin-filename "$file" # we only want to lint the staged changes, not any un-staged changes
  if [ $? -ne 0 ]; then
    echo "ESLint failed on staged file '$file'. Please check your code and try again. You can run ESLint manually via npm run eslint."
    exit 1 # exit with failure status
  fi
done

Thanks. Very helpful.

Thanks. Very helpful.

Option --diff-filter=d should be specified in git diff to exclude deleted files.

Option --diff-filter=d should be specified in git diff to exclude deleted files.

@Fer0x Where would that go?

@Fer0x Where would that go?

@alberth8 It'd be like this -> git diff --diff-filter=d --cached --name-only

@alberth8 It'd be like this -> git diff --diff-filter=d --cached --name-only

Thanks @dahjelle! Great stuff :)

Thanks @dahjelle! Great stuff :)

Thank you very much

Thank you very much

eslint is quite slow when it runs against my entire project, this is much faster, thanks!!

eslint is quite slow when it runs against my entire project, this is much faster, thanks!!

Has anyone figured out a workflow for using the --fix flag during this pre-commit hook?

What I've come across is that when the pre-commit hook is triggered for files that are staged, the new changes aren't included in the commit.

It makes sense why it wouldn't be included: this is changing a staged file, and those changes would also have to be staged.

lint-staged has a partly-working fix for this, however, and as they note, this doesn't work for partially-staged files, AKA files whose changes have been cherry-picked for a commit.

Has anyone figured out a workflow for using the --fix flag during this pre-commit hook?

What I've come across is that when the pre-commit hook is triggered for files that are staged, the new changes aren't included in the commit.

It makes sense why it wouldn't be included: this is changing a staged file, and those changes would also have to be staged.

lint-staged has a partly-working fix for this, however, and as they note, this doesn't work for partially-staged files, AKA files whose changes have been cherry-picked for a commit.

@SalTor take a look at this. It works well for me.

@SalTor take a look at this. It works well for me.

Thank you very much.

Thank you very much.

One-liner version of the above:

git diff --diff-filter=d --cached --name-only | grep -E '\.(js|jsx)$' | xargs -I % sh -c 'git show ":%" | eslint --stdin --stdin-filename "%";'

One-liner version of the above:

git diff --diff-filter=d --cached --name-only | grep -E '\.(js|jsx)$' | xargs -I % sh -c 'git show ":%" | eslint --stdin --stdin-filename "%";'

you can do this in one line git diff --cached --name-only | grep ".js$" | xargs ./node_modules/.bin/eslint

you can do this in one line git diff --cached --name-only | grep ".js$" | xargs ./node_modules/.bin/eslint

nice, @richistron

nice, @richistron

@jancimajek's one-liner is great but does not handle spaces (and other funny chars) in the filename. Using git diff -z with xargs -0 handles that nicely: luuuis/pre-commit.sh.

The @richistron one liner will lint the changed files in the local checkout, which is not necessarily what is being committed to Git if you have not staged every hunk in a file.

@jancimajek's one-liner is great but does not handle spaces (and other funny chars) in the filename. Using git diff -z with xargs -0 handles that nicely: luuuis/pre-commit.sh.

The @richistron one liner will lint the changed files in the local checkout, which is not necessarily what is being committed to Git if you have not staged every hunk in a file.