Alright everyone, I have solved it with a workaround. However, I am still looking for an actual solution. If you know the answer to my problem, please respond!
Now here's my code:
CSS:
#hidden{
display: none;
width: 1px;
height: 1px;
visibility: hidden;
}
HMTL:
<script type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js"></script>
<div id="hidden">
<div id="share-helper"></div>
</div>
JavaScript:
function Share(id){
addthis.button("#share-helper", {}, {url: "http://example.org", title: "Example Title"});
$('#share-helper').trigger('click');
}