Check Javascript Version on client and server

[tarekahf]

Sometimes, I use a javascript function and it works fine on the client. For example, object.defineProperty(), it works on the client, but it causes the entire script object to fail on the server, and it's a real pain to discover this situation.

How to check what is the Javascript version used on the server? And how to know what is the version used on the client?

Tarek