Just reading around the full screen API and implementing as i read for fun a small wrapper

fullscreenMode.js

// http://hacks.mozilla.org/2012/01/using-the-fullscreen-api-in-web-browsers/

function fullscreenMode()
{
    this.request = function() {
        var documentElement = document.documentElement;
        if (documentElement.requestFullscreen) {
            return documentElement.requestFullscreen();
        }
        else if (documentElement.mozRequestFullScreen) {
            return documentElement.mozRequestFullScreen();
        }
        else if (documentElement.webkitRequestFullScreen) {
            return documentElement.webkitRequestFullScreen();
        }
    };
    
    this.exit = function() {
        if (document.exitFullscreen) {
            return document.exitFullscreen();
        }
        else if (document.mozCancelFullScreen) {
            return document.mozCancelFullScreen();
        }
        else if (document.webkitCancelFullScreen) {
            return document.webkitCancelFullScreen();
        }
    };
    
    this.isEnabled = function() {
        var documentElement = document.documentElement;
        if (documentElement.requestFullscreen) {
            return document.fullscreen;
        }
        else if (documentElement.mozRequestFullScreen) {
            return document.mozFullScreen;
        }
        else if (documentElement.webkitRequestFullScreen) {
            return document.webkitIsFullScreen;
        }
    };
    
    this.onModeChange = function(f) {
        document.addEventListener("fullscreenchange", function () {
            f(this.isEnabled());
        }, false);

        document.addEventListener("mozfullscreenchange", function () {
            f(this.isEnabled());
        }, false);

        document.addEventListener("webkitfullscreenchange", function () {
            f(this.isEnabled());
        }, false);
    };
}