You can replace the standard alert, confirm, and prompt dialog boxes that are provided by the browser when you call the window.alert, window.prompt and window.confirm commands. The replacement dialog boxes are called with the radalert, radprompt and radconfirm methods, correspondingly. The replacement popups are implemented using RadWindow, and are a good deal more flexible than their browser counterparts. This means that you can use the RadWindow's client-side API with them, because the JavaScript functions that are used to call them return a reference to the RadWindow object. You can modify the look and feel of most aspects of these dialogs and it's easier to get information to and from them.

A RadWindowManager must be present on the form for you to use the radalert, radconfirm, and radprompt dialogs. The RadWindow objects that implement the dialogs get the setting for their Skin property from the RadWindowManager, resulting in a dialog that blends into the design of your Web site more completely than the corresponding browser dialogs.

Unlike browser popups, which can only display text, you can pass HTML to the RadWindow popups for a richer user experience and improved usability.

Caution

The Telerik RadWindow popups are non-blocking; that is, they do not block the execution thread on the server. This is because the execution of the thread cannot be blocked by Javascript. This non-blocking feature has some important implications: The Telerik RadWindow popups are modal. That is, they block the content underneath and prevent the user from interacting with it. However, because of the non-blocking nature of the popups, there are ways to work around this modal behavior. If it is absolutely necessary that a popup is modal then the default browser popups should be used. If the non-blocking nature of the radconfirm dialog is a problem, there is a possible workaround described in the following Online Demo: Confirm Server Clicks. The general approach is to move the functionality that requires the user's input to the callback function. It has some limitations and peculiarities which are listed in the demo description (e.g. that you must be able to finish the task via JavaScript only). The following Code Library article provides a different approach that overrides the entire function: Block the execution thread with radconfirm. Be aware that the approach described there works only for elements that have a click method and there is no guarantee that it will work in all scenarios. As an alternative, you could use __doPostback() in the ClientCallback function or ajaxRequestWithTarget() if you are using RadAjaxManager (using ajaxRequestWithTarget() with radconfirm)

Since Q1 2011 the RadWindowManager offers built-in server-side methods to call the RadAlert, RadConfirm and RadPrompt dialogs.

Since Q1 2012 the RadAlert and RadConfirm offer the option to accept an URL for an image that will be displayed on the left instead of their default icon for both the server-side and client-side methods.