Use $.find() instead of getElementById()

$.find() is much more powerful and available since this is a JQuery plugin. Additionally I added found node to the callback call. It's the clean way to find out which of node in a set returned by $.find() we are dealing with right now.

```javascript
$.onAvailable(".paragraph", function(node, obj){
	console.log(node)
	console.log(obj)
})
```