How would you do this?

I’ve got a client who wants me to make this effect found on this site for his gallery:

http://www.patriziodirenzo.com/

On this site, there is a menu consisting of words that you click on. When you click on a word, the other words around it fade out of view leaving only the selected word on stage. I’ve honestly got no clue on how I could achieve this kind of effect. Anybody experienced with this type of thing here?

Thank you for any advice!