questions about gulp recipe for browserify - browserify

Question

The gulp recipes on github specifically says to use stackexchange for questions instead of bug reports, that's why I am here.
I am looking at the Browserify + Globs recipe, and I have some questions.
Question: what app.js?
bundledStream
// turns the output bundle stream into a stream containing
// the normal attributes gulp plugins expect.
.pipe(source('app.js'))
// the rest of the gulp task, as you would normally write it.
// here we're copying from the Browserify + Uglify2 recipe.
.pipe(buffer())
The example specifically is about using globs to match multiple files. Why do they specify a single app.js file? Do I need to actually have some app.js somewhere, and if so, what should be in it?
Question: is there an alternate form for this?
globby(['./entries/*.js']).then(function(entries) {
// create the Browserify instance.
var b = browserify({
entries: entries,
debug: true,
transform: [reactify]
});
the whole reason I am looking at this recipe is because I was using gulp-browserify, but it is unmaintained and doesn't have browserify(...).transform(), and I need to transform with babelify with presets: es2016, es2015. And it turns out, you can't just do the obvious thing: transform: [babelify, {presets: ['es2015','es2016']}], because this doesn't work.
Likewise, you can't just rely on the .babelrc file and a plain transform: [babelify], because that doesn't work (I see imports are working, but destructured parameters like constructor({val_a=1, val_b}) do not).
Overall, I want to convert this working task:
return gulp.src(['dev/scripts/**/*.js', '!dev/scripts/vendor/**/*.js'])
.pipe(plumber({
handleError: function (err) {
console.log(err);
this.emit('end');
}
}))
.pipe(browserify())
.pipe(gulp.dest('build/scripts'))
.pipe(rename({
suffix: '.min'
}))
.pipe(uglify())
.pipe(gulp.dest('build/scripts'))
.pipe(reload({ stream: true }))
to one that uses regular browserify, and babelify with .transform("babelify", {presets: ["es2016"]})

Answer 1

So it turns out the form you need is babelify.configure({})
My task is working in this form:
gulp.task('scripts', function () {
let scripts = ['dev/scripts/**/*.js', '!dev/scripts/vendor/**/*.js']
let bundledStream = through()
bundledStream
.pipe(source('main.min.js'))
.pipe(buffer())
.pipe(sourcemaps.init({ loadMaps: true }))
.pipe(uglify())
.pipe(plumber({
handleError: function (err) {
console.log(err)
this.emit('end')
}
}))
.pipe(sourcemaps.write('./'))
.pipe(gulp.dest('./build/scripts'))
.pipe(reload({ stream: true }))
globby(scripts).then(function(entries) {
let b = browserify({
entries: entries,
debug: true,
transform: [babelify.configure({
presets: ["es2016", "es2015"]
})]
})
b.bundle().pipe(bundledStream)
}).catch(function(err) {
bundledStream.emit('error', err)
})
return bundledStream
})