Callback Example for Promise Talk

callback-example.js

const githubApi = 'https://api.github.com';
const githubEventUrl = githubApi + '/users/machuga/events';

fetchReposForLatestActivity('machuga', console.log);

function fetchReposForLatestActivity(user, fn) {
  request(githubEventsUrlFor(user), function(allEvents) {
    fetchRepos(getThreeEvents(allEvents), function(rawRepos) {
      fn(rawRepos.map(getRepo));
    });
  });
}

function fetchRepos(events, fn) {
  var completedCount = 0;
  var repos = [];
  events.forEach(function(e) {
    request(githubRepoUrlFor(e.repo.name), function(data) {
      repos.push(data);
      completedCount += 1;
      
      if (completedCount === events.length) {
        fn(repos);
      }
    });
  });
}

function getRepo(repo) {
  return {
    author: repo.owner.login,
    avatar: repo.owner.avatar_url,
    name: repo.name,
    full_name: repo.full_name,
    url: repo.html_url,
    description: repo.description
  };
}

function getThreeEvents(events) {
  return events.slice(0, 3);
}

function githubEventsUrlFor(user) {
  return githubApi + '/users/'+user+'/events';
}

function githubRepoUrlFor(repo) {
  return githubApi + '/repos/'+repo;
}

function log(a) {
  console.log(a);
}

function request(url, fn) {
  $.getJSON(url, fn);
}

promise-example.js

const githubApi = 'https://api.github.com';


// Do things, then output results to dev console
fetchReposForLatestActivity('machuga')
  .then(console.log)
  .catch(function(err) {
    console.error(err.stack);
    throw errl
  }).then(function(x) {
    console.log("You won't see this if you re-throw");
  });

function request(url) {
  return new Promise(function(resolve, reject) {
    $.ajax({
      url,
      dataType: 'json'
    }).then(resolve).fail(function() {
      reject(new Error('Shit broke'));
    })
  });
}

// Function to kickoff
function fetchReposForLatestActivity(user) {
  return request(githubEventsUrlFor(user))
    .then(getThreeEvents)
    .then(fetchRepos)
    .then(function(rawRepos) {
      return rawRepos.map(getRepo);
    });
}

// Perform actions, wait for all to end
function fetchRepos(events) {
  return Promise.all(events.map(fetchRepo));
}

function fetchRepo(event) {
  return request(githubRepoUrlFor(event.repo.name));
}

function getRepo(repo) {
  return {
    author: repo.owner.login,
    avatar: repo.owner.avatar_url,
    name: repo.name,
    full_name: repo.full_name,
    url: repo.html_url,
    description: repo.description
  };
}

function getThreeEvents(events) {
  return events.slice(0, 3);
}

function githubEventsUrlFor(user) {
  return githubApi + '/users/'+user+'/events';
}

function githubRepoUrlFor(repo) {
  return githubApi + '/repos/'+repo;
}

function log(a) {
  console.log(a);
}