Diversos promises um após o outro

new Promise(function(resolve,reject){
   setTimeout(function(){ console.log('1500'); resolve('ok1') },1500)
}).then(
  function(result) {
    new Promise(function(resolve,reject){
       setTimeout(function(){ console.log('1500'); resolve('ok2') },1500)
    }).then(function(result){
      console.log(result);
      new Promise(function(resolve,reject){
         setTimeout(function(){ console.log('6500'); resolve('ok3') },6500)
      }).then(function(result){
         console.log('ok nivel 4'+ result)
      },function (dismiss){})


    },function (dismiss){})

  }, function (dismiss) {}
);