I was researching proper commenting practices for JavaScript and highly upvoted answer (+100) cites JSDoc-like commenting. JSDoc promotes comments like this:/** * Represents a book. * @constructor * @param {string} title - The title of the book. * @param {string} author - The author of the book. */function Book(title, author) {}From my understanding, good comments should explain why not what and the above looks like alot of what to me. Why should JavaScript be commented / documented in this way, and how does this relate to the popular why, not how commenting policy? 
Why should comments / documentation of a JavaScript function include so much?
documentation;comments
The target audience for internal comments is code maintainers.  Code maintainers should be able to tell what from the code itself.The target audience for external comments is code consumers.  Code consumers don't care about why, since they are using the code, not editing it.  Thus, external comments tend to answer what.  Code consumers need very explicit documentation, since they need to figure out which function to call, not how those functions work.