checks instagram for absent usernames which absent for some reasons: some them should be available.

index.js

const log = require('debug')('app')
const request = require('superagent')
const Promise = require('bluebird')
const H = require('highland')
const { permutations } = require('permutations-stream')
const _ = require('lodash')
const retry = require('bluebird-retry')

symbols = 'abcdefghijklmnopqrstuvwxyz0123456789_.'

function instaCall(name) {
  const startMark= process.hrtime()
  const call = request
    .get(`https://www.instagram.com/${name}/`)
  return Promise.resolve(call)
    .then(() => null)
    .catch({status: '404'}, function(e) {
      return name
    })
    .then(name => {
      const [elapsedS, elapsedNS] = process.hrtime(startMark)
      return [name, elapsedS * Math.pow(10, 9) + elapsedNS]
    })
    .catch(function(e) {
      console.log(e.message)
      console.log(e)
      throw e
    })
}

permutations(1000, symbols)
  .map(x => x.join(''))
  .reject(x =>
    _.startsWith(x, '.') ||
    _.endsWith(x, '.') ||
    !_.isNaN(Number(x))
  )
  .map(name =>
    H(retry(instaCall, {args: [name]}))
  )
  .parallel(3)
  .reject(([name]) => _.isNull(name))
  .map(x => x.join(' ') + '\n')
  .pipe(process.stdout)

package.json

{
  "dependencies": {
    "bluebird": "^3.5.0",
    "bluebird-retry": "^0.10.1",
    "chai": "^3.5.0",
    "debug": "^2.6.4",
    "highland": "^2.10.5",
    "lodash": "^4.17.4",
    "mocha": "^3.2.0",
    "permutations-stream": "git@github.com:kharandziuk/permutations-stream.git#master",
    "superagent": "^3.5.2"
  },
  "scripts": {
    "test": "mocha"
  }
}