A problem I found with generators in Javascript is that you (apparently) can only yield from within the generator function itself, not from any function called by that generator. This affects the composability of functions. For example, say I want to model blocking i&#x2F;o on top of generators. In that case, there is a low-level asynchronous mechanism (function) that yields whenever there is input. A parser function could call this mechanism. And another function could call the parser. This pattern seems logical, but isn&#x27;t possible because suddenly the complete calling hierarchy has to be generator-aware.