How do I throttle $http requests in angularjs?

Question

I'm building a UI for a data importer using angularjs. The angular app is going to be crunching through the input data source (a spreadsheet, or whatever) and sending GETs/POSTs to an API to create/update records on the server and retrieve changes, etc.

If a user is importing thousands of records, I probably don't want to be opening up thousands of ajax calls at once (not that Angular would be able to get all of the requests sent out before the first finished). My thought was to add some sort of connection pool so that it could be throttled to just 10 or 50 or so ajax calls at once.

Does angular already have a built-in means of throttling ajax calls? I know I could build one without too much trouble, but I don't want to re-invent the wheel if there's already something slick out there. Can anyone recommend any tools/plugins for that? I know there are a few for jquery, but I'm hoping to avoid jquery, as much as possible, for this project.

Answer 1

In investigating this further, I found that, according to this question and this page, browsers automatically throttle http requests to the same server to somewhere between 6 and 13 concurrent requests, and they queue up additional requests until other requests complete. So, apparently, no action is needed, and I can just let my code fly.

I looked at angular-http-throttler (suggested by nathancahill), but (1) it appears to duplicate what browsers are already doing by themselves, and (2) it doesn't (currently) appear to have a mechanism for handling error cases, so if the server doesn't respond, or if it was a bad request, it doesn't decrement the request count, thus permanently clogging up it's queue.

Letting the browser queue up too many requests at once can still cause memory/performance issues if dealing with very large amounts of data. I looked at various techniques for creating a fixed-length queue in javascript, where it can fire off a callback when a queue spot becomes available, but the non-blocking nature of javascript makes such a queue tricky & fragile... Hopefully, I won't need to go that direction (I'm not dealing with THAT much data), and the browser's throttling will be sufficient for me.