Babylon.js/Tools/Gulp/tasks/gulpTasks-watch.js

// Import Dependencies.
var gulp = require("gulp");
var webpack = require('webpack');
var webpackStream = require("webpack-stream");
var debug = require("gulp-debug");

// Read the full config.
var config = require("../config.json");

/**
 * Watch ts files from typescript .
 * Hack into the cli :-)
 */
gulp.task("srcTscWatch", function() {
    // Reuse The TSC CLI from gulp to enable -w.
    process.argv[2] = "-w";
    process.argv[3] = "-p";
    process.argv[4] = "../../src/tsconfig.json";
    require("../../../node_modules/typescript/lib/tsc.js");
    return Promise.resolve();
});

/**
 * Watch ts files and fire repective tasks.
 */
gulp.task("watch", gulp.series("srcTscWatch", function startWatch() {
    var interval = 1000;

    var tasks = [];

    config.modules.map(function(module) {
        if (config[module].build && config[module].build.webpack) {
            var library = config[module].libraries[0];
            if (library.noWatch) return;
            var outputDirectory = config.build.tempDirectory + config[module].build.distOutputDirectory;
            let wpconfig = require("../" + config[module].build.webpack);
            wpconfig.watch = true;
            // dev mode and absolute path sourcemaps for debugging
            wpconfig.mode = "development";
            wpconfig.output.devtoolModuleFilenameTemplate = "[absolute-resource-path]";
            //config.stats = "minimal";
            tasks.push(webpackStream(wpconfig, webpack).pipe(gulp.dest(outputDirectory)))
        }
        else {
            // Soon To Be Gone
            config[module].libraries.map(function(library) {
                if (library.webpack) {
                    if (library.noWatch) return;
                    var outputDirectory = config.build.tempDirectory + config[module].build.distOutputDirectory;
                    let wpconfig = require("../" + library.webpack);
                    wpconfig.watch = true;
                    // dev mode and absolute path sourcemaps for debugging
                    wpconfig.mode = "development";
                    wpconfig.output.devtoolModuleFilenameTemplate = "[absolute-resource-path]";
                    //config.stats = "minimal";
                    tasks.push(webpackStream(wpconfig, webpack).pipe(gulp.dest(outputDirectory)))
                } else {
                    tasks.push(gulp.watch(library.files, { interval: interval }, function() {
                        console.log(library.output);
                        return buildExternalLibrary(library, config[module], true)
                            .pipe(debug());
                    }));
                    tasks.push(gulp.watch(library.shaderFiles, { interval: interval }, function() {
                        console.log(library.output);
                        return buildExternalLibrary(library, config[module], true)
                            .pipe(debug())
                    }));
                    tasks.push(gulp.watch(library.sassFiles, { interval: interval }, function() {
                        console.log(library.output);
                        return buildExternalLibrary(library, config[module], true)
                            .pipe(debug())
                    }));
                }
            });
        }
    });

    console.log(tasks.length);

    return Promise.resolve();
}));