The JavaScript every movement is as ridiculous as the Java everywhere movement. It's just not practical nor does it make sense. It's difficult to maintain.
I'd ask your customer what he expects to gain from going all JavaScript and research the good and bad of each piece of the application and explain to him the good and bad of that.
>Please expound on this.
Craig Berntson
MCSD, Microsoft .Net MVP, Grape City Community Influencer