Module: Plugin

For example, when you want to work with JavaScript code which extends another library.

import { greeter } from "super-greeter";
// Normal Greeter API
greeter("Hello world");
// Now we extend the object with a new function at runtime
import "hyper-super-greeter";

The definition for “super-greeter”:

/*~ This example shows how to have multiple overloads for your function */
export interface GreeterFunction {
(name: string): void
(time: number): void
/*~ This example shows how to export a function specified by an interface */
export const greeter: GreeterFunction;

We can extend the existing module like the following:

// Type definitions for [~THE LIBRARY NAME~] [~OPTIONAL VERSION NUMBER~]
// Project: [~THE PROJECT NAME~]
// Definitions by: [~YOUR NAME~] <[~A URL FOR YOU~]>
/*~ This is the module plugin template file. You should rename it to index.d.ts
*~ and place it in a folder with the same name as the module.
*~ For example, if you were writing a file for "super-greeter", this
*~ file should be 'super-greeter/index.d.ts'
/*~ On this line, import the module which this module adds to */
import { greeter } from "super-greeter";
/*~ Here, declare the same module as the one you imported above
*~ then we expand the existing declaration of the greeter function
export module "super-greeter" {
export interface GreeterFunction {
/** Greets even better! */
hyperGreet(): void;

This uses declaration merging

The Impact of ES6 on Module Plugins

Some plugins add or modify top-level exports on existing modules. While this is legal in CommonJS and other loaders, ES6 modules are considered immutable and this pattern will not be possible. Because TypeScript is loader-agnostic, there is no compile-time enforcement of this policy, but developers intending to transition to an ES6 module loader should be aware of this.

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MHMohamed Hegazy  (53)
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Last updated: Jun 22, 2024