node.js - Mongorito: save(...).then is not a function -

i tried similar example given on readme.md file:

var mongorito = require('mongorito'); var model = mongorito.model;  mongorito.connect('mongodb://localhost:27017/cr-test');  class user extends model {   collection() {     return 'users';   } }  var user1 = new user({   name: "james gosling",   email: "user1@gmail.com",   password: "changeme" });  user1.save().then(() => {   console.log('user created'); }); 

when run node --harmony server.js error:

user1.save().then(() => {              ^  typeerror: user1.save(...).then not function     @ object.<anonymous> (...\app\server.js:24:14)     @ module._compile (module.js:398:26)     @ object.module._extensions..js (module.js:405:10)     @ module.load (module.js:344:32)     @ function.module._load (module.js:301:12)     @ function.module.runmain (module.js:430:10)     @ startup (node.js:141:18)     @ node.js:980:3 

could explain me how fix that?

the readme on github outdated, project's website states:

mongodb odm node.js based on es6 generators.

no callbacks or promises.

it uses generators, can find example of on getting started page:

'use strict';  function* saveuser () {   var user1 = new user({     name: "james gosling",     email: "user1@gmail.com",     password: "changeme"   });    yield user1.save(); } 

in order generators work, must use 'use strict;' , function* syntax. github project has additional examples.

also, starting node v4, no longer need --harmony (now synonym of --es_staging) flag generators.