Cache and AJAX Results and Javascript

AJAX is an awesome tool. AJAX requests are usually faster than regular page loads and allow for a wealth of dynamism within a page. Unfortunately many people do not properly cache request information when they can. Let me show you how I cache AJAX requests - it's super easy!

My example will use my TwitterGitter plugin to grab a user's tweets. Once we have the user's tweet information, we pull it from cache instead of making a duplicate AJAX request.

The Javascript

//our cache object
var cache = {};
var formatTweets(info) {  
	//formats tweets, does whatever you want with the tweet information
};

//event
$('myForm').addEvent('submit',function() {
	var handle = $('handle').value; //davidwalshblog, for example
	var cacheHandle = handle.toLowerCase();
	if(cache[cacheHandle]) {
		formatTweets(cache[cacheHandle]);
	}
	else {
		//gitter
		var myTwitterGitter = new TwitterGitter(handle,{
			count: 10,
			onComplete: function(tweets,user) {
				cache[cacheHandle] = tweets;
				formatTweets(tweets);
			}
		}).retrieve();
	}
});

Note that before we make the AJAX request, we check the cache object to see if we've saved this key's (the key, in this case, is the username because it is unique) information. If so, avoid the repetitive AJAX request and simply return the cached information. If the key does not exist, make the AJAX request and save the result to the cache.

Take a look at this flow:

• User requests "davidwalshblog" tweets. @davidwalshblog tweets don't exist in cache, so we go grab them from Twitter and store them in cache.
• User requests "mootools" tweets. @mootools tweets don't exist in cache, so we go grab them from Twitter and store them in cache.
• User requests "davidwalshblog" tweets again. @davidwalshblog tweets DO exist in cache, so we retrieve them from cache and avoid the ajax request.

Clearing the cache periodically is easy too!

(function() { cache = {}; }).periodical(1000 * 60 * 10); //10 minutes

Caching your AJAX results in a javascript object is a very simple system to implement and can save you many repetitive requests. Efficiency FTW!