Experience Report

Web applications are inherently event-driven and traditionally implemented using imperative callbacks in Javascript. An alternative approach for such programs is functional reactive programming (FRP). FRP offers abstractions to make event-driven programming convenient, safe and composable, but like pure functions it is isolated from the 'outside' world. In this paper we describe our experience in developing a library that binds FRP to the document object model (DOM). We describe that in its current state there are fundamental issues that do not yet have a perfect solution. We expand upon the functionality of existing FRP DOM libraries with an FRP model for DOM properties. We show that despite of some design problems a pragmatic library can be created that can be used to create web applications.