webpack/lib/AutomaticPrefetchPlugin.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
	Author Tobias Koppers @sokra
*/

"use strict";

const asyncLib = require("neo-async");
const NormalModule = require("./NormalModule");
const PrefetchDependency = require("./dependencies/PrefetchDependency");

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

class AutomaticPrefetchPlugin {
	/**
	 * Apply the plugin
	 * @param {Compiler} compiler the compiler instance
	 * @returns {void}
	 */
	apply(compiler) {
		compiler.hooks.compilation.tap(
			"AutomaticPrefetchPlugin",
			(compilation, { normalModuleFactory }) => {
				compilation.dependencyFactories.set(
					PrefetchDependency,
					normalModuleFactory
				);
			}
		);
		let lastModules = null;
		compiler.hooks.afterCompile.tap("AutomaticPrefetchPlugin", compilation => {
			lastModules = [];

			for (const m of compilation.modules) {
				if (m instanceof NormalModule) {
					lastModules.push({
						context: m.context,
						request: m.request
					});
				}
			}
		});
		compiler.hooks.make.tapAsync(
			"AutomaticPrefetchPlugin",
			(compilation, callback) => {
				if (!lastModules) return callback();
				asyncLib.forEach(
					lastModules,
					(m, callback) => {
						compilation.addModuleChain(
							m.context || compiler.context,
							new PrefetchDependency(`!!${m.request}`),
							callback
						);
					},
					err => {
						lastModules = null;
						callback(err);
					}
				);
			}
		);
	}
}
module.exports = AutomaticPrefetchPlugin;