webpack/lib/esm/ModuleChunkLoadingRuntimeModule.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support 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 { SyncWaterfallHook } = require("tapable");
const Compilation = require("../Compilation");
const RuntimeGlobals = require("../RuntimeGlobals");
const RuntimeModule = require("../RuntimeModule");
const Template = require("../Template");
const {
	getChunkFilenameTemplate,
	chunkHasJs
} = require("../javascript/JavascriptModulesPlugin");
const { getInitialChunkIds } = require("../javascript/StartupHelpers");
const compileBooleanMatcher = require("../util/compileBooleanMatcher");
const { getUndoPath } = require("../util/identifier");

/** @typedef {import("../Chunk")} Chunk */

/**
 * @typedef {Object} JsonpCompilationPluginHooks
 * @property {SyncWaterfallHook<[string, Chunk]>} linkPreload
 * @property {SyncWaterfallHook<[string, Chunk]>} linkPrefetch
 */

/** @type {WeakMap<Compilation, JsonpCompilationPluginHooks>} */
const compilationHooksMap = new WeakMap();

class ModuleChunkLoadingRuntimeModule extends RuntimeModule {
	/**
	 * @param {Compilation} compilation the compilation
	 * @returns {JsonpCompilationPluginHooks} hooks
	 */
	static getCompilationHooks(compilation) {
		if (!(compilation instanceof Compilation)) {
			throw new TypeError(
				"The 'compilation' argument must be an instance of Compilation"
			);
		}
		let hooks = compilationHooksMap.get(compilation);
		if (hooks === undefined) {
			hooks = {
				linkPreload: new SyncWaterfallHook(["source", "chunk"]),
				linkPrefetch: new SyncWaterfallHook(["source", "chunk"])
			};
			compilationHooksMap.set(compilation, hooks);
		}
		return hooks;
	}

	constructor(runtimeRequirements) {
		super("import chunk loading", RuntimeModule.STAGE_ATTACH);
		this._runtimeRequirements = runtimeRequirements;
	}

	/**
	 * @returns {string} runtime code
	 */
	generate() {
		const { compilation, chunk } = this;
		const {
			runtimeTemplate,
			chunkGraph,
			outputOptions: { importFunctionName, importMetaName }
		} = compilation;
		const fn = RuntimeGlobals.ensureChunkHandlers;
		const withBaseURI = this._runtimeRequirements.has(RuntimeGlobals.baseURI);
		const withExternalInstallChunk = this._runtimeRequirements.has(
			RuntimeGlobals.externalInstallChunk
		);
		const withLoading = this._runtimeRequirements.has(
			RuntimeGlobals.ensureChunkHandlers
		);
		const withOnChunkLoad = this._runtimeRequirements.has(
			RuntimeGlobals.onChunksLoaded
		);
		const withHmr = this._runtimeRequirements.has(
			RuntimeGlobals.hmrDownloadUpdateHandlers
		);
		const conditionMap = chunkGraph.getChunkConditionMap(chunk, chunkHasJs);
		const hasJsMatcher = compileBooleanMatcher(conditionMap);
		const initialChunkIds = getInitialChunkIds(chunk, chunkGraph);

		const outputName = this.compilation.getPath(
			getChunkFilenameTemplate(chunk, this.compilation.outputOptions),
			{
				chunk,
				contentHashType: "javascript"
			}
		);
		const rootOutputDir = getUndoPath(
			outputName,
			this.compilation.outputOptions.path,
			true
		);

		const stateExpression = withHmr
			? `${RuntimeGlobals.hmrRuntimeStatePrefix}_module`
			: undefined;

		return Template.asString([
			withBaseURI
				? Template.asString([
						`${RuntimeGlobals.baseURI} = new URL(${JSON.stringify(
							rootOutputDir
						)}, ${importMetaName}.url);`
				  ])
				: "// no baseURI",
			"",
			"// object to store loaded and loading chunks",
			"// undefined = chunk not loaded, null = chunk preloaded/prefetched",
			"// [resolve, reject, Promise] = chunk loading, 0 = chunk loaded",
			`var installedChunks = ${
				stateExpression ? `${stateExpression} = ${stateExpression} || ` : ""
			}{`,
			Template.indent(
				Array.from(initialChunkIds, id => `${JSON.stringify(id)}: 0`).join(
					",\n"
				)
			),
			"};",
			"",
			withLoading || withExternalInstallChunk
				? `var installChunk = ${runtimeTemplate.basicFunction("data", [
						runtimeTemplate.destructureObject(
							["ids", "modules", "runtime"],
							"data"
						),
						'// add "modules" to the modules object,',
						'// then flag all "ids" as loaded and fire callback',
						"var moduleId, chunkId, i = 0;",
						"for(moduleId in modules) {",
						Template.indent([
							`if(${RuntimeGlobals.hasOwnProperty}(modules, moduleId)) {`,
							Template.indent(
								`${RuntimeGlobals.moduleFactories}[moduleId] = modules[moduleId];`
							),
							"}"
						]),
						"}",
						"if(runtime) runtime(__webpack_require__);",
						"for(;i < ids.length; i++) {",
						Template.indent([
							"chunkId = ids[i];",
							`if(${RuntimeGlobals.hasOwnProperty}(installedChunks, chunkId) && installedChunks[chunkId]) {`,
							Template.indent("installedChunks[chunkId][0]();"),
							"}",
							"installedChunks[ids[i]] = 0;"
						]),
						"}",
						withOnChunkLoad ? `${RuntimeGlobals.onChunksLoaded}();` : ""
				  ])}`
				: "// no install chunk",
			"",
			withLoading
				? Template.asString([
						`${fn}.j = ${runtimeTemplate.basicFunction(
							"chunkId, promises",
							hasJsMatcher !== false
								? Template.indent([
										"// import() chunk loading for javascript",
										`var installedChunkData = ${RuntimeGlobals.hasOwnProperty}(installedChunks, chunkId) ? installedChunks[chunkId] : undefined;`,
										'if(installedChunkData !== 0) { // 0 means "already installed".',
										Template.indent([
											"",
											'// a Promise means "currently loading".',
											"if(installedChunkData) {",
											Template.indent([
												"promises.push(installedChunkData[1]);"
											]),
											"} else {",
											Template.indent([
												hasJsMatcher === true
													? "if(true) { // all chunks have JS"
													: `if(${hasJsMatcher("chunkId")}) {`,
												Template.indent([
													"// setup Promise in chunk cache",
													`var promise = ${importFunctionName}(${JSON.stringify(
														rootOutputDir
													)} + ${
														RuntimeGlobals.getChunkScriptFilename
													}(chunkId)).then(installChunk, ${runtimeTemplate.basicFunction(
														"e",
														[
															"if(installedChunks[chunkId] !== 0) installedChunks[chunkId] = undefined;",
															"throw e;"
														]
													)});`,
													`var promise = Promise.race([promise, new Promise(${runtimeTemplate.expressionFunction(
														`installedChunkData = installedChunks[chunkId] = [resolve]`,
														"resolve"
													)})])`,
													`promises.push(installedChunkData[1] = promise);`
												]),
												"} else installedChunks[chunkId] = 0;"
											]),
											"}"
										]),
										"}"
								  ])
								: Template.indent(["installedChunks[chunkId] = 0;"])
						)};`
				  ])
				: "// no chunk on demand loading",
			"",
			withExternalInstallChunk
				? Template.asString([
						`${RuntimeGlobals.externalInstallChunk} = installChunk;`
				  ])
				: "// no external install chunk",
			"",
			withOnChunkLoad
				? `${
						RuntimeGlobals.onChunksLoaded
				  }.j = ${runtimeTemplate.returningFunction(
						"installedChunks[chunkId] === 0",
						"chunkId"
				  )};`
				: "// no on chunks loaded"
		]);
	}
}

module.exports = ModuleChunkLoadingRuntimeModule;