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gulpfile.js

const gulp = require("gulp");
const webpack = require('webpack');
const WebpackMessages = require('webpack-messages');
const gulpWebpack = require('webpack-stream');
const merge = require('webpack-merge');

const SRC_DIR = "src"; //Source directory
const DIST_DIR = "dist"; //Distribution directory
const TEST_DIR = "test"; //Directory the tests live in

//...

const webpackOpts = (which)=>{
    let base = {
        mode : "development",
        context : path.resolve(__dirname, "./" + SRC_DIR + "/js"),
        entry : {
            main: "./main.js",
            OimoWorker: "./engine/OIMOWorker.js"
        },
        output : {
            //path : //handled by gulp
            filename : "[name].js",
            library : "burstGame",
            libraryTarget : "umd",
            //https://github.com/webpack/webpack/issues/6525
            //Until webpack implements a solution that solves all their
            //corner cases, this will work in NodeJS, Browser, and Webworkers
            //for us!
            globalObject: "typeof self !== 'undefined' ? self : this"
        },
        //Alias that allows us to use three/examples/js files
        //without installing another npm package or whatever...
        //Also needs the imports-loader thing mentioned farther down
        //Use like require("three-examples/loaders/ObjLoader2"); or whatever
        resolve: {
            alias : {
                "three-examples" : "three/examples/js"
            }
        },
        module : {
            rules : [{
                test: /buildInfo\.json$/,
                use: {
                    loader: path.resolve(__dirname, 'substitute-loader.js'),
                    options: substituteLoaderOptions
                }
            }, {
                test : /\.html$/,
                loader : "html-loader"
            }, {
                test : /\.(js|json)$/,
                exclude : /(node_modules|bower_components|LoaderSupport|OBJLoader2)/,
                use: [{
                    loader: 'babel-loader',
                    options: {
                        presets: [
                            ['env', {
                                "targets": {
                                    "browsers": [
                                        "last 2 versions",
                                        "IE >= 9"
                                    ]
                                }
                            }],
                        ],
                        plugins: [
                            ['transform-runtime', {
                                "regenerator": true,
                            }]
                        ],
                        cacheDirectory : true
                    }
                }, {
                    loader: 'ifdef-loader',
                    options: {
                        //OVERRIDEN IN CHILD
                        BROWSER: false,
                        NODEJS: false
                    }
                }]
            }, {
                //This will add the THREE object to all three examples files (and some extra custom ones we made)
                test : /(three[\\\/]examples[\\\/]js|(OBJLoader2|LoaderSupport)\.js$)/,
                loader : "imports-loader?THREE=three"
            }]
        },
        devtool: "source-map",
        plugins: [
            new webpack.IgnorePlugin(/worker_threads/),
            //Optimize moment by not loading any extra locales
            new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
            //Show webpack stats messages (TODO: Make our own _cool_ one)
            new WebpackMessages({
              name: which,
              logger: str => console.log(`| ${str}`)
            })
        ]
    };
    const isServer = which === "SERVER";
    const isClient = which === "CLIENT";
    const isTest = which === "TEST";
    if(isServer) {
        base = merge(base, {
            entry: {
                server: base.entry.main
            }
        });
        delete base.entry.main; //Don't generate main
        base.module.rules[2].use[1].options.NODEJS = true;
        return base;
    }
    else if(isClient){
        base.module.rules[2].use[1].options.BROWSER = true;
        return base;
    }
    else if(isTest){
        base.context = path.resolve(__dirname, TEST_DIR);
        base.entry = {
            test: "./main.js"
        };
        base.module.rules[2].use[1].options.NODEJS = true;
        return base;
    }
    throw new Error("Invalid webpack config param " + which);
}

//...

gulp.task("jsBrowser", gulp.series("buildInfo", ()=>{
    return gulp.src("./")
        .pipe(gulpWebpack( webpackOpts("CLIENT"), webpack ))
        .pipe(gulp.dest( DIST_DIR + "/js" ));
}));

gulp.task("jsServer", gulp.series("buildInfo", ()=>{
    return gulp.src("./")
        .pipe(gulpWebpack( webpackOpts("SERVER"), webpack ))
        .pipe(gulp.dest( DIST_DIR + "/server" ));
}));

//...