Calling an external file using ajax

I'm trying to create a Medium-Like editor on Wordpress. I'm using this http://ift.tt/11PgVuy I've corrected the code about embedding images, but I still have problems in embedding elements as the plugin calls via ajax this URL

http://ift.tt/1Dl7OiC

How is it possible to make an ajax request to this URL in Wordpress?

Thanks Pablo