SequelizeJS many to many

gistfile1.js

// connect
var Sequelize = require("sequelize")
var sequelize = new Sequelize('spike', 'anon', 'password', {
  logging: console.log
});

// models
var User = sequelize.define('User', {
  name: Sequelize.STRING
});

var Project = sequelize.define('Project', {
  name: Sequelize.STRING,
  status: Sequelize.TEXT
});

// associations
Project.hasMany(User, { as: 'User', as: 'contributors' });
User.hasMany(Project, { as: 'contributors' });

// execute
sequelize.sync({force: true}).then(function () {
  User.create({name: 'u1'}).then(function (user1) {
    Project.create({name: 'p1'}).then(function (project1) {
      user1.addContributor(project1).then(function () {
        user1.getContributors().then(function (projects) {
          console.log('User has '+projects.length+ ' projects');
        })
      });
    });
  });
});