window.addEventListener("load", function(){
    if(window.self === window.top) return; // if w.self === w.top, we are not in an iframe
    function send_height_to_parent_function(){
        var height = document.getElementsByTagName("html")[0].clientHeight;
        //console.log("Sending height as " + height + "px");
        parent.postMessage({"height" : height }, "*");
    }
    // send message to parent about height updates
    send_height_to_parent_function(); //whenever the page is loaded
    window.addEventListener("resize", send_height_to_parent_function); // whenever the page is resized
    var observer = new MutationObserver(send_height_to_parent_function);           // whenever DOM changes PT1
    var config = { attributes: true, childList: true, characterData: true, subtree:true}; // PT2
    observer.observe(window.document, config);                                            // PT3
});