remove-node-modules-recursively.js

/* --------------------------------------------------------------- *
    Remove node modules recursively in a pure functionnal way
* ---------------------------------------------------------------- */

// applying functionnal techniques from @drboolean in his egghead course
// https://egghead.io/courses/professor-frisby-introduces-composable-functional-javascript


const fs = require('fs.extra')
const path = require('path')
const {last} = require('lodash/fp')
const Task = require('data.task')
const {List} = require('immutable-ext')

// getSubfolders :: Path -> Task _ (List Path)
const getSubfolders = folderPath => new Task((_, res) => res(
  List(fs.readdirSync(folderPath))
    .filter(file => fs.statSync(path.join(folderPath, file)).isDirectory())
    .map(file => path.join(folderPath, file))
))

// isNodeModules :: Path -> Bool
const isNodeModules = folderPath => last(folderPath.split('/')) === 'node_modules'

// getNodeModules :: Path -> Task _ (List Path)
const getNodeModules = basePath =>
  getSubfolders(basePath)
    .chain(subfoldersPaths =>
      subfoldersPaths
        .traverse(Task.of, folderPath =>
          isNodeModules(folderPath)
            ? Task.of([folderPath])
            : getNodeModules(folderPath)
        )
    )
    .map(xxs => xxs.reduce((acc, xs) => acc.concat(xs), List()))

// rmrf :: Path -> Task Error Path
const rmrf = filePath => new Task((rej, res) => {
  fs.rmrf(filePath, err => {
    if (err) rej(err)
    else res(filePath)
  })
})

// basePath :: Task Error Path
const basePath = new Task((rej, res) => {
  const param = process.argv.slice(2)[0]
  return param ? res(param) : rej(new Error(`
    No base path given!
    you have to specify one by typing \`npm start /path/to/base/folder\`
  `))
})

// removeNodeModules :: Task Error (List ())
const removeNodeModules =
  basePath
    .chain(getNodeModules)
    .chain(nodeModulePaths => nodeModulePaths.traverse(Task.of, rmrf))

module.exports = removeNodeModules


// index.js

const removeNodeModules = require('./removeNodeModules')

removeNodeModules.fork(
  err => console.log(err.message),
  removedPaths => console.log(
    'Success!',
    'here are the paths that have been removed : \n',
    removedPaths.toJS()
  )
)

// =>
//    Success!
//    here are the paths that have been removed :
//    [ ... ]