How to create node.js module using Typescript

Question

The very simple module that I've created to test the viability of this endeavor. Here is the beginning of SPServerApp.ts:

class SPServerApp {
    public AllUsersDict: any;
    public AllRoomsDict: any;
    constructor () {
        this.AllUsersDict = {};
        this.AllRoomsDict = {};
    }
}
module.exports = SPServerApp();

Then in my app, I have this require statement:

var serverapp = require('./SPServerApp');

I then try to access one of the dictionaries like so:

serverapp.AllUsersDict.hasOwnProperty(nickname)

But get the error:

TypeError: Cannot read property 'hasOwnProperty' of undefined

Can anybody see what I am doing wrong here?

Thanks, E.

You aren't instantiating the class. Add 'new' or create a new instance where you're requiring it. — Phix
– Phix, Commented Aug 14, 2016 at 1:53
I think this link will help you. stackoverflow.com/questions/23739044/… — Lasantha Basnayake
– Lasantha Basnayake, Commented Aug 15, 2016 at 5:23

Jens · Accepted Answer · 2016-08-15 06:22:28Z

The problem is that you forgot the 'new' keyword when calling the constructor. The line should read:

module.exports = new SPServerApp();

If you don't use new your constructor will be treated as a normal function and will just return undefined (since you did not return anything explicitly). Also 'this' will not point to what you expect within the constructor.

Omitting new in Node is actually quite common. But for this to work you have to explicitly guard against new-less calls in the constructor like so:

constructor () {
    if (! (this instanceof SPServerApp)) {
        return new SPServerApp();
    }
    this.AllUsersDict = {};
    this.AllRoomsDict = {};
}

BTW, in TypeScript you can also use module syntax. The TS compiler will translate this into the export/require statements. With ES6 style modules your example would look like this:

export class SPServerApp {
    public AllUsersDict: any;
    public AllRoomsDict: any;
    constructor () {
        this.AllUsersDict = {};
        this.AllRoomsDict = {};
    }
}
export var serverapp = new SPServerApp();

In your other TS file you just import:

import { serverapp } from './SPServerApp';

serverapp.AllUsersDict.hasOwnProperty('something');

Collectives™ on Stack Overflow

How to create node.js module using Typescript

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related