index.js

// Promises

// Core:

// 1. What is fetch and how does it relate to AJAX? What does fetch return? Give a very basic example of fetch.

// AJAX is the terminology that encompasses all the different methods for making HTTP requests from our JavaScript. The two things we need for AJAX to work are: the XMLHTTPRequest() object, and JavaScript itself.

// The way in which fetch relates to AJAX is that fetch is a function makes an HTTP request and is therefore one way in which we can make AJAX requests.

// Promise

const handlePokemon = (pokemon) => {
  pokemon.forEach((poke) => {
    console.log(poke)
  })
}

const promise = fetch('https://pokeapi.co/api/v2/pokemon')
promise
  .then((response) => {
    return response.json()
  })
  .then((data) => {
    const pokemon = data.results
    handlePokemon(pokemon)
  })
  .catch((err) => console.log(err))

// 2. Why do we use promises?

// To handle the eventual completion or failure of an asynchronous operation

// 3. What are the names of the functions that are related to handling promises (that are called when the promise is fulfilled or fails).

// resolve(), reject()

// resolve() === .then
// reject() === .catch

new Promise((resolve, reject) => {})

// 4. https://edstem.org/courses/4230/lessons/2859/slides/21316

const parseRandomUser = (promise) => {
  promise.then((user) => console.log(user))
}

const getRandomUser = (callback) => {
  fetch('https://randomuser.me/api/')
    .then((response) => {
      const promise = response.json()
      callback(promise)
    })
    .catch((err) => console.log(err))
}

getRandomUser(parseRandomUser)

// Advanced:

// 5.

// Write a function called evenPromise that returns a promise. evenPromise will take one argument (which will be expected to be a number), and calls resolve if the number is even, and reject if the number is odd. Pass a string as an argument to the resolve and reject functions that reflects these different outcomes. Now call evenPromise and console.log out the data that results from success and error through the appropriate functions.

const evenPromise = (num) => {
  return new Promise((resolve, reject) => {
    if (num % 2 === 0) {
      resolve('the number is even')
    } else {
      reject('the number is odd')
    }
  })
}

evenPromise(3)
  .then((message) => console.log(message))
  .catch((errMessage) => console.log(errMessage))