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(2); greeter("Hello world"); // Now we extend the object with a new function at runtime import "hyper-super-greeter"; greeter.hyperGreet();

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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Last updated: Aug 05, 2020