Refresh parent page partially from iframe without reloading the iframe using javascript in asp.net

Last time we talked about Refreshing the parent page from child window in asp.net using javascript. This technique is useful in many scenarios. (If you haven't been through How to open new window in asp.net using javscript and C-sharp, I would like to suggest to read the post thoroughly. After this you will clearly see why the stuff we are talking about in this post is important.) But programmers using iframe to load another asp.net web page may wonder if we could only partially refresh the parent page so that iframe keeps itself from reloading. This can by done by calling the parent page javascript function from the child page loaded in the iframe. This way we can even avoid the need of ajax to refresh the parent page without affecting the iframe content. As usual I have presented the simple practical approach to tell you as much clearly as possible - follow please. And before continuing, I would like to inform that there is a post regarding Frequent question on parent and child page refresh, reload, function call in asp-net using javascript that discusses, in aggregate, about some more approaches of parent and child page operations.
Parent Asp.net Page

I am the parent page.

        

    

Page to be loaded in parent page iframe

I am content of iframe page.

    
    

Visualize the output

What's in the code?
You see a button in the child page that is loaded in the iframe of parent page. On click of the button, the javascript function displayMessageFromIframeChild() of the parent page is called. This function displays the string message from child page in a div of the parent page. That's all. Happy programming!