I know both language well and I use them in my work, so I can handle them pretty easily and that is why I bid lower than others. Do you need a Javascript library for your code? That will be the way we call it JS closure, such that when come to integration, all you need to do is just load a lib file.
However, please be reminded, not all Python functions can be converted to JS code. For example, we can use python to manipulate local files, but we can not do the same with JS.
So I assume that the task must be doable in the first place. Let me know what you think about it. Thanks!