pre-commit

What is pre-commit?

The pre-commit npm package allows you to easily manage and run scripts before committing code to a repository. It helps enforce code quality and consistency by running tasks such as linting, testing, and formatting before the commit is finalized.

What are pre-commit's main functionalities?

Running Linting Scripts

This feature allows you to run linting scripts before committing code. The provided code sample configures the pre-commit hook to run ESLint on all files in the repository.

{
  "scripts": {
    "precommit": "eslint ."
  }
}

Running Tests

This feature allows you to run tests before committing code. The provided code sample configures the pre-commit hook to run the tests defined in the npm test script.

{
  "scripts": {
    "precommit": "npm test"
  }
}

Running Multiple Scripts

This feature allows you to run multiple scripts before committing code. The provided code sample configures the pre-commit hook to run both linting and testing scripts sequentially.

{
  "scripts": {
    "precommit": "npm run lint && npm test"
  }
}

Other packages similar to pre-commit

husky

Husky is a popular package for managing Git hooks, including pre-commit hooks. It offers more flexibility and features compared to pre-commit, such as support for all Git hooks, easy integration with other tools, and better configuration options.

lint-staged

Lint-staged is a package that works well with pre-commit hooks to run linters on staged files. It is often used in conjunction with Husky to ensure that only the files that are staged for commit are linted, which can improve performance and efficiency.

README

pre-commit

pre-commit is a pre-commit hook installer for git. It will ensure that your npm test (or other specified scripts) passes before you can commit your changes. This all conveniently configured in your package.json.

But don't worry, you can still force a commit by telling git to skip the pre-commit hooks by simply committing using --no-verify.

Installation

It's advised to install the pre-commit module as a devDependencies in your package.json as you only need this for development purposes. To install the module simply run:

npm install --save-dev pre-commit

To install it as devDependency. When this module is installed it will override the existing pre-commit file in your .git/hooks folder. Existing pre-commit hooks will be backed up as pre-commit.old in the same repository.

Configuration

pre-commit will try to run your npm test command in the root of the git repository by default unless it's the default value that is set by the npm init script.

But pre-commit is not limited to just running your npm test's during the commit hook. It's also capable of running every other script that you've specified in your package.json "scripts" field. So before people commit you could ensure that:

• You have 100% coverage
• All stying passes.
• JSHint passes.
• Contribution licenses signed etc.

The only thing you need to do is add a pre-commit array to your package.json that specifies which scripts you want to have ran and in which order:

{
  "name": "437464d0899504fb6b7b",
  "version": "0.0.0",
  "description": "ERROR: No README.md file found!",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: I SHOULD FAIL LOLOLOLOLOL \" && exit 1",
    "foo": "echo \"fooo\" && exit 0",
    "bar": "echo \"bar\" && exit 0"
  },
  "pre-commit": [
    "foo",
    "bar",
    "test"
  ]
}

In the example above, it will first run: npm run foo then npm run bar and finally npm run test which will make the commit fail as it returns the error code 1. If you prefer strings over arrays or precommit without a middle dash, that also works:

{
  "precommit": "foo, bar, test"
  "pre-commit": "foo, bar, test"
  "pre-commit": ["foo", "bar", "test"]
  "precommit": ["foo", "bar", "test"],
  "precommit": {
    "run": "foo, bar, test",
  },
  "pre-commit": {
    "run": ["foo", "bar", "test"],
  },
  "precommit": {
    "run": ["foo", "bar", "test"],
  },
  "pre-commit": {
    "run": "foo, bar, test",
  }
}

The examples above are all the same. In addition to configuring which scripts should be ran you can also configure the following options:

• silent Don't output the prefixed pre-commit: messages when things fail or when we have nothing to run. Should a boolean.
• colors Don't output colors when we write messages. Should be a boolean.
• template Path to a file who's content should be used as template for the git commit body.

These options can either be added in the pre-commit/precommit object as keys or as "pre-commit.{key} key properties in the package.json:

{
  "precommit.silent": true,
  "pre-commit": {
    "silent": true
  }
}

It's all the same. Different styles so use what matches your project. To learn more about the scripts, please read the official npm documentation:

https://npmjs.org/doc/scripts.html

And to learn more about git hooks read:

http://githooks.com

License

MIT