@netlify/git-utils/README.md

Utility for dealing with modified, created, deleted files since a git commit

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# Git Utility

Utility for dealing with modified, created, deleted files since a git commit.

## Usage

```js
/* Export the Netlify Plugin */
export const onPreBuild = function ({ utils }) {
  const { git } = utils

  /* Do stuff if files modified */
  if (git.modifiedFiles.length !== 0) {
    console.log('Modified files:', git.modifiedFiles)
  }

  /* Do stuff only if html code edited */
  const htmlFiles = git.fileMatch('**/*.html')
  console.log('html files git info:', htmlFiles)

  if (htmlFiles.edited.length !== 0) {
    console.log('>> Run thing because HTML has changed\n')
  }
  //
  /* Do stuff only if markdown files edited */
  const markdownFiles = git.fileMatch('**/*.md')
  console.log('markdown files git info:', markdownFiles)

  if (markdownFiles.modified.length !== 0) {
    console.log('>> Run thing because Markdown files have been created/changed/deleted\n')
  }

  /* Do stuff only if css files edited */
  const cssFiles = git.fileMatch('**/*.css')
  if (cssFiles.deleted.length !== 0) {
    console.log('>> Run thing because css files have been deleted\n')
    console.log(cssFiles)
  }
}
```

## API

The `git` util includes the following signature.

```js
export const onPreBuild = function ({ utils }) {
  console.log(utils.git)
  // {
  // fileMatch: [Function], <-- Lookup function. See below
  // modifiedFiles: [ Array of all modified files ],
  // createdFiles: [ Array of all created files ],
  // deletedFiles: [ Array of all deleted files ],
  // commits: [ Array of commits with details ],
  // linesOfCode: [AsyncFunction: linesOfCode] <-- how many lines of code have changed
  // }
  //
}
```

`git.fileMatch()` is a glob matcher function to detect the git status of a pattern of files.

```js
export const onPreBuild = function ({ utils }) {
  const cssFiles = utils.git.fileMatch('**/*.css')
  console.log('cssFiles', cssFiles)
  // {
  // modified: [ 'just-changed.css', 'just-changed-two.css' ],
  // created: [ 'just-added.css' ],
  // deleted: [ 'just-deleted.css' ],
  // edited: [ 'just-changed.css', 'just-changed-two.css', 'just-added.css', 'just-deleted.css' ]
  // }
  //
}
```

## Prior art

This was originally found in [danger.js](https://danger.systems/js/) and extracted into this utility