您可以从单个Nodejs模块导出多个类吗？

Question

Currently, I have 4 Child Classes each in their own file. I'm requiring them all in the same file. I am wondering if I can contain all 4 of those classes in a single module. Currently, I'm importing them like this

var Jack = require('./Jack.js');
var JackInstance = new Jack();
var Jones = require('./Jones.js');
var JonesInstance = new Jones();

I'd like to import them like this

var People = require('./People.js');
var JackInstance = new People.Jack();

Or even

var Jack = require('./People.js').Jack;
var JackInstance = new Jack();

My classes are defined like so

class Jack{
    //Memeber variables, functions, etc
}

module.exports = Jack;

Answer 1

You can export multiple classes like this:

eg People.js

class Jack{
   //Member variables, functions, etc
}

class John{
   //Member variables, functions, etc
}

module.exports = {
  Jack : Jack,
  John : John
}

And access these classes as you have correctly mentioned:

var People = require('./People.js');
var JackInstance = new People.Jack();
var JohnInstance = new People.John();

Answer 2

You can also do this in a shorter form, using destructuring assignments (which are supported natively starting from Node.js v6.0.0 ):

// people.js
class Jack {
  // ...
}

class John {
  // ...
}

module.exports = { Jack, John }

Importing:

// index.js
const { Jack, John } = require('./people.js');

Or even like this if you want aliased require assignments:

// index.js
const {
  Jack: personJack, John: personJohn,
} = require('./people.js');

In the latter case personJack and personJohn will reference your classes.

A word of warning:

Destructuring could be dangerous in sense that it's prone to producing unexpected errors. It's relatively easy to forget curly brackets on export or to accidentally include them on require .