JS Safari Reader source code.
safari-reader.js: Directly download from http://blog.manbolo.com/2013/03/18/safari-reader-source-code
safari-reader.source.js: Copy pasted source from Safari browser in april 2015
safari-reader.src.beautified.js: Same code run through a beautifier.
Open safari web inspector.
Disable (pause) Javascript in the Safari console debugger.
Open a web page like this one (http://blog.manbolo.com/2012/11/20/using-xcode-opengl-es-frame-capture) (no affiliation).
It does not work on any web page (the page needs to be "readable" and have no other JS errors, otherwise you wont see the source pop out).