Promise example

promise1.js

// -------------------------------------------------------------------
// this function simulates a request that needs to run async
// -------------------------------------------------------------------
function favoriteBlogger(favorite) {
  return new Promise((resolve, reject) => {
    if (favorite === 'rajatexplains') {
      resolve(favorite);
    } else {
      reject('your preference is poor😛');
    }
  });
}

// -------------------------------------------------------------------
// this is the code that actually loads data
// -------------------------------------------------------------------

// 🚫 this doesn’t work
function getFavoriteBloggerBroken() {
  // the return value is a Promise, not the value that resolved the Promise
  const blogger = favoriteBlogger('rajatexplains');

  // that means we can’t return the value from this function 😱
  console.log(`My favorite blogger is a ${blogger}.`);
  //=> My favorite blogger is a [object Promise].
}

// ✅ this works
function getFavoriteBlogger() {
  const blogger = favoriteBlogger('rajatexplains');

  // we can only get to the value using the `.then` chain
  blogger.then((value) => {
    console.log(`My favorite blogger is a ${value}.`);
    //=> My favorite blogger is a rajatexplains.
  });
}

getFavoriteBlogger();