aherve

import { expect } from 'chai'
describe('Stuff', () => {
  
  // -------THE CALLBACK WAY------- //
  it('looks ugly with callbacks', (done) => {
    User.count({}, (err, count) => {
      if (err) { return done(err) }
      expect(count).to.be.above(1)
      User.findOne({}, (err, user) => {
        if (err) { return done(err) }

aherve

// ----- Without async ----- //
function regularPlusOne (i: number): Promise<number> {
  return new Promise(resolve => {
    resolve(i + 1)
  })
}

// ----- With async ----- //
async function plusOne (i: number): Promise<number> {
  return i + 1

aherve

async function notSure (userId: string | null): Promise<null | User> {
  if (!userId) { return null } // e.g. return void
  const user = await User.findById(userId) // this return the result of the promise of findById
  if (user) { return user }
  throw 'User not found'
}

aherve

async function demo (userId: string) {
  try {
    const user = await User.findById(user)
    const result = await doSomethingAsync(user)
    finalResult(user, result)
  } catch (e) {
    dealWithIt(e)
  }
}

aherve

function demoPromise (userId) {
  User
  .findById(userId)
  .then(user => {
    doSomethingAsync(user)
    .then(result => {
      finalResult(user, result)
    })
  })
}

aherve

function demoPromise (userId) {
  User
    .findById(userId)
    .then(doSomethingAsync) // doSomething will receive `user` as argument if everything goes smoothly
    .catch(dealWithIt) // here we catch both the `findById` and `doSomethingAsync` errors at once
}

aherve

function demoCb (userId) { 
  User.findById(userId, (err, user) => {
    if (err) { dealWithIt(err) }
    doSomethingAsync(user, (err, result) => {
      if (err) { dealWithIt(err) }
      // and so it goes...
    })
  })
}

aherve

aherve

#!/usr/bin/env ruby
class Reducer
  attr_accessor :key, :game_type, :user_id

  def initialize(key,value)
    @key = key

    #split the primary key to get user_id and game type:
    @game_type,@user_id = key.split("|")

aherve

chess|1 1
chess|1 1
chess|2 1
chess|2 2
go|1    2
chess|1 1
go|1    1
go|1    1
chess|2 2
go|1    1