Programming for web browsers is attractive. Such a program can be run by any one, any where, and everyone knows how to access it: Any one with access to a computer can load a web page and this runs whatever program is associated with that page. There is a sophisticated environment for making web pages easily available.
ProscriptLS is a WAM-based implementation of Prolog with HTML document builtins and a Procedure Box Control Flow interactive debugger. The debugger uses a JQuery terminal running a ProscriptLS interpreter as an element of a web page. The debugger is implemented along the lines presented in the LogicForSystems-1 technical note.
There is an example use of ProscriptLS to create a simple calculator here.