ES6Modules.js

// userdata.js

class User {
    constructor(name) {
        this.name = name;
    }
}

export class Item {
    constructor(name) {
        this.name = name;
    }
}

export const CONST = 'Jack';
export let func = () => { };

export default User;

let privateVar = 1;

// Export an object 
export { 
    User as default, 
    Item,
    CONST, 
    func 
};
  
 // main.js
  import User from './userdata' // Import from export default

import {CONST,func} from './userdata' // Import from export

// Alias
import {
    CONST as JACK,
    func as myfunc
} from '.userdata'

// Import from export default + export
import User, {CONST,func} from './userdata'

// Import all
import * as UserData from './userdata' 
UserData.User
const {CONST,func} = UserData // Destructuring object

// Import library
import underscore ;

// React style
import React, { Component, PropTypes } from 'react';