Issues with window.print() onLoad

Question

I'm trying to open the print dialog when a page is done loading. Using the code below, I get no errors and the window opens, but the onload never seems to fire and the print dialog does not open (Firefox and Chrome -- haven't tested other browsers).

I've tried these :

var printWindow = window.open(result.url);

printWindow.window.onload = function () {
    printWindow.window.print();
    console.log("Printing page");
}

and

var printWindow = window.open(result.url);

printWindow.onload = function () {
    printWindow.print();
    console.log("Printing page");
}

and

var printWindow = window.open(result.url);
printWindow.addEventListener("load", function() {
    printWindow.print();
    console.log("Got here");
});

An example of what the result.url looks like:

http://ourserver/arcgis/rest/directories/arcgisoutput/OurTools/Print_Tool_Adv_GPServer/_ags_WebMap_de458080-c19a-11e6-8ade-005056a65a05.PDF

I'm trying to see if this post applies to my case, and how I can use the answer to my advantge. My original window that allows the user to generate the new url is at http://ourserver/ourapp whereas the new url is at http://ourerver/arcgis/... I don't believe this is the same situation, but I am trying to see how it is possible to exploit the answer of the suggested duplicate if this is the case.

UPDATE So I finally got the signal to fire using a postMessage approach. However, I think i'm running into a window.print() specific problem, because the print statement comes up to the console, but I still have the following issues:

• On chrome, no print dialog opens

• On Firefox, print dialog opens, but it prints about:blank, and not the url I'd opened the window with...seems like the page hadn't loaded completely before the dialog opened or something (same thing that happens when I call printWindow.print() directly without a handler).

    var printWindow = window.open(result.url);
  
    var eventMethod = window.addEventListener ? "addEventListener" : "attachEvent";
    var eventer = window[eventMethod];
    var messageEvent = eventMethod == "attachEvent" ? "onmessage" : "message";
  
    // Listen to message from child window
    eventer(messageEvent,function(e) {
      console.log('origin: ', e.origin)
  
    // Check if origin is proper
    if( e.origin != 'http://ourserver' ){ return }
      console.log('parent received message!: ', e.data);
  
      try {
        //attempt to deserialize function and execute as closure
        eval('(' + decodeURI(e.data) + ')();');
      } catch(e) {}
    }, false);
  
    printWindow.opener.postMessage({serializeFunction(openPrintDialog)}, 'http://ourserver');
  

The code references these functions:

  function serializeFunction(f) {
    return encodeURI(f.toString());
  }

  function openPrintDialog() {
    printWindow.print();
    console.log("Got here");
  }