This webpage explores what is and what is not allowed by SOP
when JavaScript in a webpage tries to access and possibly
modify other parts of that webpage. As the name suggest,
content (incl. JavaScript code) from some origin is only
allowed to access resources that come from the same origin.
Click ANYWHERE IN THIS SENTENCE to change the frame.
And click ANYWHERE IN THIS SENTENCE TO change it back.
Accessing the JavaScript functions of the inner frame is
only allowed if it comes from the same origin.