webpack/lib/runtime/StartupEntrypointRuntimeModule.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 RuntimeModule = require("../RuntimeModule");
const { entryModuleIdExpression } = require("../javascript/StartupHelpers");

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

class StartupEntrypointRuntimeModule extends RuntimeModule {
	/**
	 * 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;
	}

	/**
	 * @param {boolean} asyncChunkLoading use async chunk loading
	 */
	constructor(asyncChunkLoading) {
		super("startup entrypoint");
		/** @type {boolean} */
		this.asyncChunkLoading = asyncChunkLoading;
	}

	/**
	 * Generates runtime code for this runtime module.
	 * @returns {string | null} runtime code
	 */
	generate() {
		const compilation = /** @type {Compilation} */ (this.compilation);
		const { runtimeTemplate, chunkGraph } = compilation;
		const chunk = /** @type {Chunk} */ (this.chunk);
		const cst = runtimeTemplate.renderConst();
		return `${
			RuntimeGlobals.startupEntrypoint
		} = ${runtimeTemplate.basicFunction("result, chunkIds, fn", [
			"// arguments: chunkIds, moduleId are deprecated",
			`${cst} moduleId = chunkIds;`,
			`if(!fn) chunkIds = result, fn = ${runtimeTemplate.returningFunction(
				`${RuntimeGlobals.require}(${entryModuleIdExpression(
					chunkGraph,
					chunk,
					"moduleId"
				)})`
			)};`,
			...(this.asyncChunkLoading
				? [
						`return Promise.all(chunkIds.map(${RuntimeGlobals.ensureChunk}, ${
							RuntimeGlobals.require
						})).then(${runtimeTemplate.basicFunction("", [
							`${cst} r = fn();`,
							"return r === undefined ? result : r;"
						])})`
					]
				: [
						`chunkIds.map(${RuntimeGlobals.ensureChunk}, ${RuntimeGlobals.require})`,
						`${cst} r = fn();`,
						"return r === undefined ? result : r;"
					])
		])};`;
	}
}

module.exports = StartupEntrypointRuntimeModule;