prettier-if-modified

Run prettier only on modified files.

This module uses file attributes to keep track of when files have been modified and formatted. Only files that were modified after they have been formatted will be passed on to prettier to be formatted again. As such, this module enables incremental formatting for codebases of all sizes.

Usage

Non-incremental:

prettier --write "**/*.js"

Incremental:

prettier-if-modified "**/*.js" -- prettier --write

With .prettierignore:

prettier-if-modified --ignore-path .prettierignore "**/*.js" -- prettier --write

Algorithm

// WARNING: THIS IS SIMPLIFIED PSEUDOCODE
 
let all_files = find_files('**/*.js')
 
let modified_files = all_files.filter(file => {
  let last_modified = get_attribute(file, 'last_modified')
  let last_formatted = get_attribute(file, 'last_formatted')
  return last_modified > last_formatted
})
 
prettier(modified_files)
 
let last_formatted = Date.now()
modified_files.forEach(file => {
  set_attribute(file, 'last_formatted', last_formatted)
})

Development

# Install dependencies 
yarn install
 
# Format source code 
yarn format

License

MIT © Mark Tiedemann