source: frontend/node_modules/webpack/lib/PrefetchPlugin.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
*/

"use strict";

const PrefetchDependency = require("./dependencies/PrefetchDependency");

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

const PLUGIN_NAME = "PrefetchPlugin";

class PrefetchPlugin {
        /**
         * Creates an instance of PrefetchPlugin.
         * @param {string} context context or request if context is not set
         * @param {string=} request request
         */
        constructor(context, request) {
                if (request) {
                        this.context = context;
                        this.request = request;
                } else {
                        this.context = null;
                        this.request = context;
                }
        }

        /**
         * Applies the plugin by registering its hooks on the compiler.
         * @param {Compiler} compiler the compiler instance
         * @returns {void}
         */
        apply(compiler) {
                compiler.hooks.compilation.tap(
                        PLUGIN_NAME,
                        (compilation, { normalModuleFactory }) => {
                                compilation.dependencyFactories.set(
                                        PrefetchDependency,
                                        normalModuleFactory
                                );
                        }
                );
                compiler.hooks.make.tapAsync(PLUGIN_NAME, (compilation, callback) => {
                        compilation.addModuleChain(
                                this.context || compiler.context,
                                new PrefetchDependency(this.request),
                                (err) => {
                                        callback(err);
                                }
                        );
                });
        }
}

module.exports = PrefetchPlugin;