Ask HN: One ajax call or two simultaneous calls? Which is faster?

pedalpete · on Sept 18, 2008

I was considering a similar issue not long ago and decided on one call for the following reasons 1) user percieved speed - I can't control the users bandwidth, or memory, and two ajax calls means two pages being retrieved by the users browser, and then two different functions to place those pages into the users browser 2) error handling - what if there is an error with the image or comments? the user will get one portion returned, and not the other (minor disconnects happen all the time and usually it isn't detrimental, but the more ajax calls, the more opportunity for failure).

In the end I decided to do one ajax call and the split the returned data into two strings and place them on the page.

You can check out the results at www.HearWhere.com

Also, if you are always getting the image with related comments, I would suspect that they would both go within the same area/div of a page, so why split them?

boucher · on Sept 18, 2008

I guess I don't really understand the question. You're loading text based content, and an image, and you want to know whether or not to get everything in one XMLHTTPRequest, or to load two separate XMLHTTPRequests?

Why do you need a request at all for the image? If you've got the information you need and predictable URLs, you could use one XMLHTTPRequest, and simultaneously create an image in JavaScript and set it's source, right? This will obviously be faster than first going to your server, then creating the image in the resulting html. Of course, if you can't actually generate the image tag without hitting your server, then this is all moot.

noodle · on Sept 18, 2008

my rule of thumb, that i would apply to this situation, is keep it simple. if you want to optimize, test both options in your own app. i don't think that one can generalize this situation to say for sure which option is faster or better without also having the context of your application in mind.