Some JavaScript (ECMAScript) features are easier to understand than others. Generators look weird — like pointers in C/C++. Symbols manage to look like both primitives and objects at the same time. These features are all inter-related and build on each other….

Source: https://medium.freecodecamp.org/some-of-javascripts-most-useful-features-can-be-tricky-let-me-explain-them-4003d7bbed32