Is this even possible with jquery only with no bulky plugins?
I know there are lots of plugins and alternatives, i’m searching for the shortest, robustest & most cleanest (preferably relying on jquery)
Here basic jsfiddle to tryout your thoughts:
http://jsfiddle.net/3vPJd/
I have to go with “This is not possible” due to the fact that the parent page cannot get the height of the 3rd party page since it is from a different domain than the parent page.
Edit: It is possible to do this if you have some control of the 3rd party page.
I personally would just use the method they already have implemented, it doesn’t require jQuery, you just have to include the frame.js.
At that point, all you need is a method on the parent page that listens for when the hash changes and resizes the iframe accordingly, which is also already written by the site you linked. it is a very clean solution already, no real need to modify it. It can be found here.