I am writing a GreaseMonkey plugin in TypeScript. I am compiling main.ts file into main.js, and then put it on GreaseMonkey. The output file format looks like vanilla JavaScript, and GreaseMonkey consumes it happily. Now the project grows larger, I plan to split the code into several files. However, I failed to find a build system that works.


  • It should bundle everything into a single JavaScript file. GreaseMonkey only takes one file.
  • It should generate vanilla JavaScript. I don't think things like System.import works in GreaseMonkey.

Possible behavior


// lib.ts
export function greet(name: string) {
    console.log(`Hello, ${ name }!`);


// main.ts
import { greet } from './lib.ts';


it returns

// main.js
let lib_public = {};
lib_public.greet = function greet(name: string) {
    console.log(`Hello, ${ name }!`);

Webpack is all you need! OK, some plugins here and there(webpack, webpack-cli, typescript for obvious reasons, ts-loader for webpack-Typescript interaction/compilation), but here is the recipe, assuming your code is in src folder (Main.ts being the entry point) and you want your lib.user.js in dist folder:


// required for path resolution for dist folder
const path = require("path");
// used to access the BannerPlugin
const webpack = require("webpack");
// required for pretty format for the Userscript banner
const stripIndent = require("common-tags").stripIndent;

module.exports = {
    entry: "./src/Main.ts",
    devtool: 'inline-source-map',
    mode: "development",
    module: {
        rules: [
                test: /\.tsx?$/,
                use: 'ts-loader',
                exclude: /node_modules/
    resolve: {
        extensions: [".ts", ".js"]
    output: {
        path: path.resolve(__dirname, "dist"),
        filename: "lib.user.js"
    plugins: [
        new webpack.BannerPlugin({
            raw: true,
            banner: stripIndent`
                // ==UserScript==
                // @name    Your lib name
                // @namespace   https://path.com/your/lib/namespace
                // @version 1.0.0
                // @author  Your Name
                // @description Your lib description
                // @include https://www.example.com/*
                // @copyright   2019, Your Org
                // ==/UserScript==`

Important bits from package.json:

  "scripts": {
    "build": "webpack"
  "devDependencies": {
    "common-tags": "^1.8.0",
    "ts-loader": "^5.3.3",
    "typescript": "^3.3.1",
    "webpack": "^4.29.3",
    "webpack-cli": "^3.2.3"

Build: npm run build, which will invoke webpack, as instructed in the scripts section of package.json.


Another option is rollup. It allows compiling into one file (using iife)

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