toggle-fullscreen.js

function toggleFullScreen() {
    var doc = window.document;
    var docEl = doc.documentElement;
    var requestFullScreen = docEl.requestFullscreen || docEl.mozRequestFullScreen || docEl.webkitRequestFullScreen;
    var cancelFullScreen = doc.exitFullscreen || doc.mozCancelFullScreen || doc.webkitExitFullscreen;
    if(!doc.fullscreenElement && !doc.mozFullScreenElement && !doc.webkitFullscreenElement) { 
        requestFullScreen.call(docEl);
    }
    else {
        cancelFullScreen.call(doc);  
    }
}