webpack/lib/runtime/WorkerRuntimeModule.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
*/

"use strict";

const RuntimeGlobals = require("../RuntimeGlobals");
const HelperRuntimeModule = require("./HelperRuntimeModule");

/** @import Compilation from "../Compilation" */

class WorkerRuntimeModule extends HelperRuntimeModule {
	constructor() {
		super("worker");
	}

	/**
	 * Returns true, if the runtime module should get it's own scope.
	 * When false, `generate()` must emit complete statements ending with `;`
	 * so a following runtime IIFE is not parsed as a call (ASI).
	 * @returns {boolean} true, if the runtime module should get it's own scope
	 */
	shouldIsolate() {
		return false;
	}

	/**
	 * Generates runtime code for this runtime module.
	 * @returns {string | null} runtime code
	 */
	generate() {
		const compilation = /** @type {Compilation} */ (this.compilation);
		const { runtimeTemplate } = compilation;
		// prefer a global `Worker` when present (web, Bun, polyfills), else `worker_threads.Worker`
		const nodeWorker = runtimeTemplate.getBuiltinModule(
			runtimeTemplate.renderNodePrefixForCoreModule("worker_threads"),
			".Worker"
		);
		return `${RuntimeGlobals.worker} = typeof Worker !== "undefined" ? Worker : ${nodeWorker};`;
	}
}

module.exports = WorkerRuntimeModule;