Export full module as a constructor function

Imagine having a nodejs module where requiring it gives you a constructor function. Here's an example:

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

Now, I want to create a .d.ts declaration file that can be imported and utilized in this way:

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

Despite going through the TypeScript documentation, I am struggling to figure out how to properly define the .d.ts file. I've experimented with various combinations of class, interface, namespace, module, and export but haven't found a solution yet. Is it even possible to achieve what I described above? Any guidance would be greatly appreciated.

Answer №1

Instead of using the following code snippet

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

It is recommended to use this code instead:

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

Why the change?

import * as Mod from "mod";

The former code represents ES6 module import syntax. It indicates that the "mod" module object is imported as the local name Mod. ES6 modules can only expose properties and cannot be invoked as a function or with the new keyword.

It is worth reiterating this point as it is often overlooked: ES6 modules can only expose properties and cannot be invoked as a function or with the new keyword.

Transitioning your code to an ES6 runtime may cause it to malfunction, as there is no require function in ES6 modules. However, the "old-style" import Mod = require("mod"); is still valid.

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