index.js

const walkUp = require('walk-up-path')
const { resolve } = require('path')
const { stat: stat_, statSync } = require('fs')
const { promisify } = require('util')
const stat = promisify(stat_)

function* binDirs (start, root) {
  start = resolve(start)
  root = resolve(root)
  for (const path of walkUp(start)) {
    yield resolve(path, 'node_modules/.bin')
    if (path === root)
      break
  }
}

const fileExists = file => stat(file)
  .then(st => st.isFile())
  .catch(() => false)

const fileExistsSync = file => {
  try {
    return statSync(file).isFile()
  } catch (e) {
    return false
  }
}

const findBin = async (bin, start, root) => {
  for (const binDir of binDirs(start, root)) {
    const path = resolve(binDir, bin)
    if (await fileExists(path))
      return path
  }
  return null
}

const findBinSync = (bin, start, root) => {
  for (const binDir of binDirs(start, root)) {
    const path = resolve(binDir, bin)
    if (fileExists(path))
      return path
  }
  return null
}

exports.binDirs = binDirs
exports.findBin = findBin
exports.findBinSync = findBinSync