CODEWITHSUNDEEP
javascriptjqueryajax
Vael Victus
Vael Victus

Reputation: 209

Why cache AJAX with jQuery?

I use jQuery for AJAX. My question is simple - why cache AJAX? At work and in every tutorial I read, they always say to set caching to false. What happens if you don't, will the server "store" such requests and get "clogged up"? I can find no good answer anywhere - just links telling you how to set caching to false!

Upvotes: 2

Views: 523

Answers (7)

user535617
user535617

Reputation: 644

The browser caches the information, not the server. The point in using Ajax is usually because you're going to be getting information that changes. If there's a part of a website or something you know isn't going to change, you don't bother with it more than once (in which case, caching is ok), that's the beauty of Ajax. Since you should only be dealing with information that may be changing, you want to get the new information. Therefore, you don't want the browser to cache.

For example, Gmail uses Ajax. If caching was simply left on you wouldn't see your new e-mail for quite awhile, which would be bad.

Upvotes: 0

Jennifer Grucza
Jennifer Grucza

Reputation: 377

Here's a hypothetical scenario. Say you want the user to be able to click any word on your page and see a tooltip with the definition for that word. The definition is not going to change, so it's fine to cache it.

Upvotes: 1

Nick Craver
Nick Craver

Reputation: 630449

It's not that the server stores requests (though they may do some caching, especially higher volume sites, like SO does for anonymous users).

The issue is that the browser will store the response it gets if instructed to (or in IE's case, even when it's not instructed to). Basically you set cache: false if you don't want to user's browser to show stale data it fetched X minutes ago for example.

If it helps, look at what cache: false does, it appends _=190237921749817243 as a query string pair (random number, the actual one is the current time, so it's always....current). This forces the browser to make the request to the server for data again, since it doesn't know what that query string means, it may be a different page...and since it can't know or be sure, it has to fetch again.

Upvotes: 4

DoctorLouie
DoctorLouie

Reputation: 2674

If you don't turn it off you'll have issues trying to figure why you AJAX works but your functions aren't responding as you'd like them to. Forced re-validation at the header level is probably the best way to gain a cache-less assimilation of the data being AJAX'd in.

Upvotes: 1

Ned Batchelder
Ned Batchelder

Reputation: 375634

The server won't cache the requests, the browser will. Remember that browsers are built to display pages quickly, so they have a cache that maps URLs to the results last returned by those URLs. Ajax requests are URLs returning results, so they could also be cached.

But usually, Ajax requests are meant to do something, you don't want to skip them ever, even if they look like the same URL as a previous request.

If the browser cached Ajax requests, you'd have stale responses, and server actions being skipped.

Upvotes: 2

James Sumners
James Sumners

Reputation: 14777

The problem is, as always, Internet Explorer. IE will usually cache the whole request. So, if you are repeatedly firing the same AJAX request then IE will only do it once and always show the first result (even though subsequent requests could return different results).

Upvotes: 0

Kyle Humfeld
Kyle Humfeld

Reputation: 1907

The main problem with caching requests in any kind of dynamic environment is that you'll get stale data back some of the time. And it can be unpredictable when you'll get a 'fresh' pull vs. a cached pull.

If you're pulling static content via AJAX, you could maybe leave caching on, but how sure are you that you'll never want to change that fetched content?

Upvotes: 0

Related Questions