index.js

require('pm2')()

  .create({
     script   : '/tmp/hello.js',
     instances: 'max',
   }, function(err, started) {
     console.log('Successfully started %s processes', started.length)
   })

   .list(function(process_list) {
     console.log(process_list);
   })

   .then(function() {
     this.restart('all')
   });

index2.js

require('pm2')()

  .then(function() {
    this.create({
      script   : '/tmp/hello.js',
      instances: 'max',
   })

  .then(function(ret) {
     console.log(ret);
     return this.list();
   })

  .then(function(list) {
     console.log(list);
     return this.restart('all');
   });