(question was answered)

You shouldn't be concerned. I'm a JavaScript developer and this is what my roadmap would look like.

1. HTML & CSS
2. Sass instead of CSS
3. Full Stack JavaScript course. (I personally skip everything jQuery because it technically can all be done with pure JavaScript and jQuery is a heavy framework for your website (performance, etc).
4. Fill in the missing gaps like ES6 using the single courses under Library.
5. Make sure you understand node.js and express and the use of SQL and Mongo databases in node.js backends.
6. Learn a few front-end frameworks, just the basics first and explore the one you love the most or see the most potential in.
7. By this moment, you will know what your strengths and weaknesses are and will know what to do next. :)

About your ES6 concerns, there are several single courses in the Library covering let, const, arrow functions... An overview of the full ES6 features can be found here.

In the end: Yes, I can make a complete application with things I learned here, but take in mind. Having to Google stuff is normal. As a developer, I google questions and errors 20 times a day to figure out the best method. I struggled a lot at the start with combining all the things I learned seperately but don't be afraid. Learning takes time, it's not always fun, but in the end, you'll get there :)