[Discussion] Ideas for new Concepts

### Concept Roadmap
There are already a lot of ideas for additional concepts that we could cover with concept exercises in the future.
You can find a list in our roadmap document: **[Roadmap - Potential Future Concepts](https://exercism.org/docs/tracks/javascript/roadmap#h-potential-future-concepts)**

We already created issues for the following new concepts/exercises:
- [x] https://github.com/exercism/javascript/issues/1009
- [x] https://github.com/exercism/javascript/issues/1015 (claimed)
- [ ] https://github.com/exercism/javascript/issues/1502 (claimed)
- [x] https://github.com/exercism/javascript/issues/1506
- [x] https://github.com/exercism/javascript/issues/1515 (claimed)
- [x] https://github.com/exercism/javascript/issues/1528 (claimed)
- [x] https://github.com/exercism/javascript/issues/1500
- [x] https://github.com/exercism/javascript/issues/1501

Additionally some concept exercises that exist but need major improvements are not yet visible on the website (status "wip"), see https://github.com/exercism/javascript/issues/1415.

### Purpose of this issue
- Suggest additional concepts to cover that are not on the [roadmap](https://github.com/exercism/javascript/blob/main/reference/roadmap.md#syllabus-overview) yet.
- Comment on which concept from the roadmap you would like to see implemented first.
- Volunteer for creating a certain concept exercise that does not have an issue yet, so a maintainer can write up an issue with some basic guidelines for you.
- General discussion about how to divide concepts/ how to structure the concept tree.
- etc