ajax request browser limit

Question

A more generic questions to start. Is there a limit to the response size of an ajax request, if it is a JSON request?

I am passing large amounts of data through a JSON request and running into a 'script stack quota is exhausted' message in FF3. Now in FF2 the quota was 4mb but in FF3 it is 640kb. I am wondering if this is JSON specific somehow. Do normal ajax requests have a response size limit? One that may be imposed by the browser? If a non-JSON request doesn't have these same issues with script stack quota, how could I categorize the data coming back? XML perhaps...Im not sure if I would be within the bounds of the w3c spec with my data to do so.

Answer 1

I suspect the limits are different if you are sending vs receiving data, so I am going to assume it is around sending data to the client. JSON is just a data type, really. What you are really doing, is suspect, is making a GET request for a javascript script which should be limited to a reasonable size. The wiki for JSON also says use the XMLHTTPRequest method, which might get around your limit, but you would still need a proxy to avoid cross-domain scripting limitations and use a more sensible mime-type, like html, xml, binary, etc. If you are putting any images in the JSON remember that they can be links as there are no cross-domain issues with those requests.

Double check as well that it is not the number of requests causing you trouble, browsers have limits there too. Sometimes as low as 2.

Answer 2

As a general rule I try to keep my AJAX data small. If I have to pass a large amount of data I will retrieve it with multiple calls. So if I am loading a table, I will have one method that will tell me how many records are going to be returned, and another method to return me the records in groups of # (usually 20 for me).

The good part about doing this is that I can load the page as I retrieve data, and the user is not waiting for one large payload.

Also, it would be better to use JSON rather than XML. JSON is usually a smaller payload than XML, and many tests have show that it is easier for the Browser to load it in.

Answer 3

iirc this was a bug on FF3 last year but I believe (yes, checked it here) it's fixed. Looking down the comments though, there's this note:

Note: this test is dependent upon architecture and available memory. On a x86_64 machine with 2G and a 64bit build, it will fail with InternalError: script stack space quota is exhausted however on a x86_64 with 4G and a 64bit build it will pass.

The comments also read that this is a pure JS problem, which means although the data format will strictly not matter, very large chunks of JSON might blow the JS stack where XML strings might not. I think you just have to try.

OTOH, it is marked fixed, so there's a question of making sure you're on the latest version of FF too.

Answer 4

I haven't encountered any tangible limit, but your user interactivity, break up the large data into multiple calls. Large tables take forever to get transferred through ajax, especially if the user is running IE. Large data + Ajax + IE = IE crash.

Answer 5

I think annakata is right.

The text of the error message also suggest that the problem is occurring due to the depth of your json structure, not the KB size of it.

What it means is that when you eval your json, JavaScript engine uses a stack during parsing the json. This stack is hitting its maximum limit due to the depth (number of nested elements) in your json structure.

You might want to check whether somewhat flatter structure is feasible for your requirements.