Practice JS Promise

practice-promise.js

const posts = [
  {title: 'Post 1', body: 'this is post 1'},
  {title: 'Post 2', body: 'this is post 2'},
  {title: 'Post 3', body: 'this is post 3'},
];
 
// Callback way
// function createPost(post, callback){
//   setTimeout(function(){
//     posts.push(post);
 
//     callback();
//   }, 2000);
// }
 
// function getPosts(){
//   setTimeout(function(){
//     let output = '';
//     posts.forEach(function(post){
//         output += `<li>${post.title}</li>`;
//     });
 
//     document.body.innerHTML = output;
//   }, 1000);
// }
 
// createPost({title: 'Post 4', body: 'this is post 4'}, getPosts);

// Promise way (promise is better than using callback)
function createPost(post){
  return new Promise(function(resolve, reject){
    setTimeout(function(){
      posts.push(post);

      let err = false;

      if( !err ){
        resolve();
      } else {
        reject('Something went wrong!');
      }

      resolve();
    }, 2000);
  });
}
 
function getPosts(){
  setTimeout(function(){
    let output = '';
    posts.forEach(function(post){
        output += `<li>${post.title}</li>`;
    });
 
    document.body.innerHTML = output;
  }, 1000);
}
 
createPost({title: 'Post 4', body: 'this is post 4'})
.then(getPosts)
.catch(function(response){
  document.body.innerHTML = response;
});