How to pass variables and/or launch functions from child pages to parent in iFrames?

Does this method I have found on the web apply?

(onchildevent)
      // Send the message "Hello" to the parent window
      // ...if the domain is still "davidwalsh.name"
      parent.postMessage(this.document.body.scrollHeight,"http://www.parent.page");

Since we now have hold of the window, we can postMessage to it:
// Create IE + others compatible event handler
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('parent received message!:  ',e.data);
},false);

i.g. frames are handled like windows, hence they follow the same origin policy
if both windows (parent and your iframe) use content from the same domain i.e. some.tld, then you need to set each window's document.domain to the corresponding value
if they are from different domain, they cannot access each other, you need a proxy page then

AHoffmann - it is a cross origin messaging

http://ajaxian.com/archives/using-html-5-postmessage

oops, sorry not reading proper and giving old fashioned answer :-/

This question is identical to:

https://www.experts-exchange.com/questions/27556193/HTML-and-JavaScript-iFrame-resize-trouble-how-to-fit-dynamically-a-framed-page-with-variable-height.html

asked by the same poster and still open.

@mplungjan: I will test the addEventListener monday.
@Mr.Virmaior: unfortunately, I did not receive this code adapted to the question you mention. Would it be something like this? If so, where to paste formulas? Only in the frame page or also in the parent page?

(frame page body) onclick(function(this.name)) {  
  var myFRMHGT = document.getElementById(this.name).body.offsetHeight;  
  window.parent.frames['myFrame'].postMessage(myFRMHGT);        
}  
   
var onmessage = function(this.name) {  
  var data = document.getElementById(this.name).data;  
  var origin = document.getElementById(this.name).origin;  
  document.getElementById('myFrame').style.height = data;  
}
     
if (typeof window.addEventListener != 'undefined') {  
  window.addEventListener('message', onmessage, false);  
} else if (typeof window.attachEvent != 'undefined') {  
  window.attachEvent('onmessage', onmessage);  
}

One nmore question: the if(e.origin == 'http://origin-domain.com') { declaration can only be done when the page in online? I actually get an error if I type only the page name.

I've requested that this question be closed as follows:

Accepted answer: 0 points for Sar1973's comment #37766846

for the following reason:

Was an auto answer.

This code is not functionally different from the code I provided you with in https://www.experts-exchange.com/questions/27556193/HTML-and-JavaScript-iFrame-resize-trouble-how-to-fit-dynamically-a-framed-page-with-variable-height.html.

Not at all: I solved it using a postMessage method, not encapsulating.

I will make a note never to participate in questions you ask again.  That way, we will both be happier.

I have not deprecated your answer or said you are not reliable as expert: just appointed that did not fit to my request, which was to pass the height variable from frame to parent (while your code does not).
I do not understand then why I should enter in your "black list".