nem035

version: 2

jobs:

  # job that installs our dependencies
  # and persists them to the workspace
  # so other jobs can use them
  install:
    working_directory: ~/enki-project
    docker:

nem035

workflows:
  version: 2
  install_build_lint_deploy:
    jobs:
      - install
      - build:
          requires:
            - install
      - lint:
          requires:

nem035

version: 2

jobs:
  build:
    working_directory: ~/enki-project
    machine: true
    environment:
      - ENKI: 'example'
    steps:
      - checkout

nem035

const p = new Promise(function(resolve) {
  resolve(Math.random());
});

// both of these statements give the same output
p.then(console.log);
p.then(console.log);

nem035

function all(arrayOfPromises) {
  return new Promise(function (resolve, reject) {
    // initialize an array of results with length of the given array of promises
    const results = Array.from(Array(arrayOfPromises.length));

    // since all promises are started in parallel (quickly one after the other)
    // we are using a counter to keep track of when they all resolve because
    // each promise can take a different amount of time to resolve
    let resultsLeft = arrayOfPromises.length;

nem035

console.log("first");

// enqueue a Task after this Task
setTimeout(function() {
  console.log("fourth");
}, 0);

// enqueue a microtask within this Task
Promise.resolve()
  // enqueue a microtask after this microtask

nem035

console.log(1);

new Promise(function(resolve) {
  console.log(2); // this gets logged right after 1
  resolve();
}).then(function() {
  console.log(4);
});

console.log(3);

nem035

// this
Promise.resolve(3);

// is practically the same as
new Promise(function(resolve) {
  resolve(3);
});

// and this
Promise.reject(3);

nem035

// promise chains allow us to write clean vertical code
// that is much more readable
// (no need for any reject calls either because promises
// propagate errors by default)
function getThing(arg) {
  return getStuff(arg)
    .then(getMoreStuff)
    .then(getThatFinalThing);
}

nem035

// nesting promises is an anti-pattern
// as with callbacks, we end up with a
// "pyramid of doom"
function getThing(arg) {
  return new Promise(function (resolve, reject) {
    getStuff(arg)
      .then(function (stuff) {
        getMoreStuff(stuff)
          .then(function (moreStuff) {
            getThatFinalThing(moreStuff)