Js Promise chaining

app.js

var p  = new Promise(function(resolve, reject){
  
  var name = 'anoop';
  resolve(name);
  var name = 'error'
  //reject(name);
})

p.then(addLastName)

.catch( handle);


function addLastName(name){
  
  //  console.log(name+'rai');
  //return name+'rai'
  var p  = new Promise(function(resolve, reject){
    
    var name = 'anoop';
    //resolve(name);
    var name = 'error'
    reject(name);
  })

  return p;
}

function showName(name){
  console.log(name);
}

function handle(name){
  console.log(name);
}

Promises are different then events in these ways-

1- They are called only once.
2- we can have simple chaining then nested and complex chaining.
3- They are wrapped in try catch block
4- If a promise return any value , that itself becomes then-able.
5- Promise can be handled once it is already settled unlike eventHandlers we can't handle an event before setting eventHandlers.