get_all_dependencies.js

const axios = require('axios')
const start = new Date

function fetchDependencies(url) {
  console.log('Fetching ' + url) 
  return axios.get(url).then(({data})=> {
    return data.dependencies || []
  }, () => {
    return []
  }).catch(() => {
    return []
  })
}

async function getAllDependencies(packageName) {
  const dependencies = new Set()
  const visited = new Set()
  let started = 0
  let completed = 0

  return new Promise(resolve => {

    function _fetch(name) {
      const url = `http://registry.npmjs.org/${name}/latest`

      if (visited.has(url)) {
        return Promise.resolve()
      }
      visited.add(url)

      started += 1
      const promise = fetchDependencies(url).then(deps => {

        for (const key in deps) {
          dependencies.add(key)
          _fetch(key)
        }

      }).finally(() => {
        completed += 1

        if (completed === started) {
          resolve([...dependencies])
        }
      })
    }
    _fetch(packageName)
  })
}

getAllDependencies('forever').then(res => {
  console.log(res)
  console.log(res.length)
  console.log((new Date - start) / 1000 + ' sec')
}).catch(console.error)