window.open(url) function to open an Url on new browser window.
Developers can post a form to new window or build a data entry page. window.open(url) function is simple but if it opens new browser several times then overall application could become overwhelming.
We can use ModalPopupExtender instead of window.open function. ModalPopupExtender is an Ajax Control Toolkit to create a modal popup. Modal popup is a dialog box that always on top of a page. You cannot access parent page if modal popup still appear so you need to close it first.
I already have a blog post explaining and showing example about ModalPopupExtender, please follow this Create a PopUp Dialog with ModalPopupExtender AjaxControlToolkit
ModalPopupExtender usually has a Panel Control and inside this Panel we can have any control like label, textbox, button etc. ModalPopupExtender usually has an OK and Cancel button inside Panel.
Those OK and Cancel buttons actually close the modal popup.
The question is how can we open an Url and show it inside Modal Popup? We can just fill in the Url’s HTML source code string into Panel inside the Modal Popup.
So that we can have dynamic content on that modal popup
One way to get Url’s HTML source code is using WebRequest Class. This WebRequest Class can get the response stream of Url and we convert it to string using StreamReader Class.