This paper presents a semantics, in denotational style, for a simplified version of the Hop Web programming language. This semantics focuses on the organization of programs. It shows how programs initially run on servers elaborate expressions to be evaluated by clients i.e. JavaScript interpreters within web browsers. Conversely, it shows how client-side expressions may interact with servers. The presented semantics also formalizes how server-side and client-side expressions share variables and values.