Add a '.throttle' method about promise-utils

[ftrimble]

I think this is already implemented in promiseUtils.mapLimit - what would you want from that function that isn't already built in?

[ftrimble]

Also, fwiw - I'm not sure that as written your code actually implements the throttling correctly. Since you've already created the promises, they are going to get executed whether you are awaiting them or not. You need to only invoke the function that generates the promise when there is sufficient remaining concurrency to deal with it.

[rjnienaber]

Sorry, you're absolutely right not sure how I missed it when looking through the docs. promiseUtils.mapLimit is what I'm looking for!

The promiseThrottle function will work because of promiseFuncs.shift()() which will invoke the function that returns the promise which will then start executing.

[ftrimble]

ah ya i didn't notice that the original map returned a lambda, not just invoked one.