Slyncr is a project mainly written in JavaScript, it's free.
bookmarklet for controlling slideshows from a remote site
Slyncr is a bookmarklet that will listen for commands from a remote website, primarily intended for controlling slides from a mobile phone.
Right now, the supported sites are 280slides.com, Scribd.com's html mode, and any site that uses the arrow keys to control the slides like Google Docs.
This will eventually be an npm package, but as of now, make sure you've got the socket.io, express, and ejs npm packages. SSL support is also needed.