How to open a web page automatically in full screen mode

function cancelFullScreen(el) {
            var requestMethod = el.cancelFullScreen||el.webkitCancelFullScreen||el.mozCancelFullScreen||el.exitFullscreen;
            if (requestMethod) { // cancel full screen.
                requestMethod.call(el);
            } else if (typeof window.ActiveXObject !== "undefined") { // Older IE.
                var wscript = new ActiveXObject("WScript.Shell");
                if (wscript !== null) {
                    wscript.SendKeys("{F11}");
                }
            }
        }