Tech Report CS-09-04

Flapjax: A Programming Language for Ajax Applications

Leo Meyerovich, University of California, Berkeley, Arjun Guha, Brown University, Jacob Baskin, Google, Greg Cooper, Google, Michael Greenberg, University of Pennsylvania, Aleks Bromfield, Brown University and Shriram Krishnamurthi, Brown University

April 2009


This paper presents Flapjax, a language designed for contemporary Web applications. These applications communicate with servers and have rich, interactive interfaces. Flapjax provides two key features that simplify writing these applications. First, it provides event streams, a uniform abstraction for communication within a program as well as with external Web services. Second, the language itself is reactive: it automatically tracks data dependencies and propagates updates along those dataflows. This allows developers to write reactive interfaces in a declarative and compositional style. Flapjax is built on top of JavaScript. It runs on unmodified browsers and readily interoperates with existing JavaScript code. It is usable as either a programming language (that is compiled to JavaScript) or as a JavaScript library, and is designed for both uses. This paper presents the language, its design decisions, and illustrative examples drawnfrom several working Flapjax applications.

(complete text in pdf)