Gulp, Browserify, & Babel Example

gulpfile.js

var gulp = require('gulp');
var browserify = require('browserify');
var babelify = require('babelify');
var source = require('vinyl-source-stream');
var buffer = require('vinyl-buffer');

gulp.task('js', function () {
    return browserify('src/main.js')
        .transform('babelify', {presets: ['env']})
        .bundle()
        .pipe(source('app.js')) // Readable Stream -> Stream Of Vinyl Files
        .pipe(buffer()) // Vinyl Files -> Buffered Vinyl Files
        // Gulp Plugins Here
        .pipe(gulp.dest('dist'));
});

gulp.task('watch', function () {
    gulp.watch('src/**/*.js', gulp.series('js'));
});

gulp.task('default', gulp.series('js', 'watch'));