CODE EXAMPLE FOR JAVASCRIPT

.catch() in promise will aslo return a promise

// Throwing an error will call the catch method most of the time
var p1 = new Promise(function(resolve, reject) {
  throw new Error('Uh-oh!');
});

p1.catch(function(e) {
  console.error(e); // "Uh-oh!"
});

// Errors thrown inside asynchronous functions will act like uncaught errors
var p2 = new Promise(function(resolve, reject) {
  setTimeout(function() {
    throw new Error('Uncaught Exception!');
  }, 1000);
});

p2.catch(function(e) {
  console.error(e); // This is never called
});

// Errors thrown after resolve is called will be silenced
var p3 = new Promise(function(resolve, reject) {
  resolve();
  throw new Error('Silenced Exception!');
});

p3.catch(function(e) {
   console.error(e); // This is never called
});