How to properly nest functions returning Promises (ECMA6) in node.js (Nested Promises example)

promises.js

/*

  How to properly nest functions returning Promises (ECMA6) in node.js (Nested Promises example)

  generated output (with 1 second ticks) =>
    p1 function
    p2 function
    p3 function
    p3 done
    p2 done
    p1 done

*/

function first() {
  return new Promise(function(resolve, reject) {
    setTimeout(function() {
      console.log('p1 function');
      var p2 = second().then(function(){
        console.log('p2 done');
        resolve();
      });
    }, 1000);
  });
}

function second() {
  return new Promise(function(resolve2, reject2) {
    setTimeout(function() {
      console.log('p2 function');
      var p3 = third().then(function(){
        console.log('p3 done');
        resolve2();
      });
    },1000);
  });
}

function third() {
  return new Promise(function(resolve3, reject3) {
    setTimeout(function() {
      console.log('p3 function');
      resolve3();
    },1000);
  });
}



first().then(function() {
  console.log('p1 done');
})
.catch(function(e) {
  console.log('error', e);
});