JQuery .data() how to work question

Question

I have a question about .data(). In a stackoverflow answer, jquery saves data in cache object where cache index is suffixed with a hash of the dom element. For example, consider

Answer 1

The way in which jQuery data works is by storing all the data internal in a variable called cache. Each jQuery session creates a "expando" which is basically a random string like jquery161362319162 specific to that session. This is placed on each object in the DOM such as element.jquery161362319162 with a value of the index in cache.

Here is a very basic example of roughly how it works. This will need a bit more work to add support for multiple data on an element, but you'll get the idea of how it works internally.

var cache = []; // Stores all the data for each element
var uid = 'jquery89437507043'; // random generated id,
                               // jQuery uses a function to automatically
                               // generate such a value

function data(element, key, data)
{
    if (data !== undefined) // We are setting data
    {
        var thisCache[key] = data;
        cache.push(thisCache)
        element[uid] = cache.length; // Place the index cache
                                        // for this data set on the element
    }
    else
    {
        return cache[element[uid]][key];
    }
}

Usage

var div = $('div').get(0);
data(div, 'test', { 'apple': 'juice' });

alert(data(div, 'test').apple); // Will alert 'juice'