For this question I'm going to give a simplified example of what I want to do, and the function I want to learn to write.

var collection = '';

<div id='container'>
    <span>1</span>
    <span>2</span>
    <span>3</span>
</div>

What I want to do this, for every span in the div, take its text, add it to the collection.

So ideally it would look like:

$('#container').addtoCollection(collection);

The method would be something like:

$(this).find('span').each(function () {
    collection = collection + $(this).text();
}).

Where the first this would equal #container.

So in the end you can do:

console.log(collection);

and get:

123

How do I write the function that does this?

Thanks!