Export entire module as constructor

Question

Say I have a nodejs module that, when I require it, it returns a constructor function to me. Something like the following:

var Mod = require("modulename");
var mod = new Mod();
mod.method();

I want to write a .d.ts declaration file that can be imported and used like so:

import * as Mod from "mod";
let mod = new Mod();
mod.method();

I've tried reading all the documentation on the Typescript website but it's honestly as clear as mud, and I feel like I've tried every combination of class, interface, namespace, module and export that exists in my .d.ts file. I'm wondering if the above is even achievable. Can anybody offer any help?

Answer 1

Instead of writing this

import * as Mod from "mod";
let mod = new Mod();

You should write this

import Mod = require("mod");
let mod = new Mod();

Why?

import * as Mod from "mod";

This is ES6 module import syntax. It says you're importing the "mod" module object into the local name Mod. ES6 modules only expose properties, and cannot be invoked as a function or with new.

I'll say this again because people often don't believe me or choose to ignore it: ES6 modules only expose properties, and cannot be invoked as a function or with new.

If you start compiling your code to an ES6 runtime (instead of downleveling to ES5 modules with CJS / AMD), your code will stop working. There's no require function in ES6 modules, though, so the "old-style" import Mod = require("mod"); is still OK.