example-promise.js

function getTempCallback (location, callback) {
  callback(undefined, 78);
  callback('City not found');
}

getTempCallback('London', function(err, temp) {
  if (err) {
    console.log('error', err);
  } else {
    console.log('success', temp);
  }
});

function getTempPromise (location) {
   return new Promise(function (resolve, reject) {
     setTimeout(function () {
       resolve(79);
       reject('City not found');
     }, 1000);
   });
 }

getTempPromise('Philadelphia').then(function (temp) {
   console.log('promise success', temp);
 }, function (err) {
   console.log('promise error', err);
 });

 // Challenge Area
function addPromise (a, b) {
  return new Promise(function (resolve, reject) {
    if (typeof a === 'number' && typeof b === 'number') {
      resolve(a + b);
    } else {
      reject('A & b need to be numbers');
    }
  });
}

addPromise(2, 3).then(function (sum) {
  console.log('success', sum);
}, function (err) {
  console.log('error', err);
});

addPromise('andrew', 9).then(function (sum) {
  console.log('this should not show up');
}, function (err) {
  console.log('This should appear', err);
});