gulp browserify babelify

gulpfile.js

const spawn = require("child_process").spawn;
const gulp = require( 'gulp' );
const babel = require( 'gulp-babel' );
const babelify = require("babelify");
const browserify = require("browserify");
const source = require( "vinyl-source-stream" );
const buffer = require( 'vinyl-buffer' );
const uglify = require( 'gulp-uglify' );

function reload ()
{
    var p;
    gulp.watch("gulpfile.js", spawnChildren);
    var spawnChildren = function(callback) {
        if (p) p.kill();
        p = spawn( "gulp", ["default"], { stdio: "inherit" });
        if (callback) callback();
    }();
}

function js(){
    return browserify("./app.js")
		.transform(babelify)
		.bundle()
		.pipe(source("app.js"))
		.pipe(buffer())
		.pipe(babel())
		.pipe(uglify({ mangle: { toplevel: true } }))
		.pipe(gulp.dest("./dist"));
}

gulp.watch( [ './app.js', './src/*.js' ], js );
gulp.watch( [ "./gulpfile.js"], reload);

exports.default = js;