Recursive file search by pattern

index.js

module.exports = function findFilesByPattern (pattern, dir = process.cwd()) {
  const check = (name, file) => {
    const newFile = path.join(name, file)
    return new Promise((resolve, reject) => {
      fs.stat(newFile, (err, stats) => {
        if (err) return reject(err)
        if (stats && stats.isDirectory()) return resolve(readDir(newFile))
        if (pattern.exec(newFile)) return resolve(newFile)
        return resolve()
      })
    })
  }

  const readDir = (name) =>
    new Promise((resolve, reject) =>
      fs.readdir(name, (err, files) =>
        err ? reject(err) : resolve(Promise.all(
          files.map(check.bind(null, name))
        ))))
        .then(values =>
          values.reduce((x, y) => x.concat(y), [])
                .filter(value => value))

  return readDir(dir)
}

Recursive_file_search_by_pattern.md

Recursive file searching can be helpful if you are building a tool like jest or gest. For example, jest searches for files that match /(/__tests__/.*|\\.(test|spec))\\.(ts|tsx|js)$/i, and gest looks for /.*.(query|graphql|gql)$/i. I wanted to test my functional programming abilities and try to tackle this recursive problem as functionally as possible.

Implementation below

Example Usage

const gest = Gest(schema, options)

findFilesByPattern(/.*.(query|graphql|gql)$/i)
  .then(values =>
    Promise.all(values.map(v =>
      readFile(v)
        .then(gest))))
  .catch(console.log)