source: trip-planner-front/node_modules/webpack/lib/AutomaticPrefetchPlugin.js

/*
        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;