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Manipulating a Separate Window

For this article I'll be using some code from the Windows Script Component (WSC) section of this site. When viewing the ShellInfo WSC example, there are links that provide additional information on Special Folder names and Environment Variables. This information is displayed in a pop-up window, and this window (if it remains open) is used to fulfill subsequent requests for additional information..

Some basic introductory information:
	This window can be referenced by using `self`
	The `window` object has a `location` property which is an object with properties and methods relating to the URL associated with the `window` object.
	The `search` property of the `location` object specifies the Query String passed to web applications like CGI scripts or Active Server Pages (ASP) scripts.

Demonstration

Environment variables

Special folders

Requirements

Mange the open/closed state of the window.
Dynamically specify the windows's document.
Close the window when it is no longer needed.

To manage the state of the window-that is to determine whether or not it has been open and remains open-an object variable is used to store a reference to the opened window. The name property is the key element. It is specefied when the window is first open, and is set to an empty string when the window is closed (handled in onUnload), making it possible to know if the user closed the window.

	var wHelp = new Object();
	wHelp.name = "";
		...
	if ( wHelp.name != "" ) { // window is already open
		...
	} else { // window is not open
		...
	}

The document is specified when the window is first open, as the first argument passed to self.open().

	self.open(url, name, features);

In this application the same URL is maintained. The document is generated by a CGI script, and its contents depend on the value passed in the Query String. All that needs changing is the Query String. This is done by setting the search property of the location property of the window object (window.location.search). When the search property is changed a request is made to the server with the new Query String.

	wHelp.location.search = "?item=" + s;

Closing the window is accomplished with the window object's close() method. When the document in the parent window is unloaded a confirmation dialog box is displayed asking the user if the child window should be closed, and conditionally self.close() is called.

	if ( wHelp.name != "" ) {
		if ( confirm("Would you like to close the help window?") ) {
			wHelp.close();
		}
	}

The openHelp(s) function below is where all the work is done to open the window or change the document in it.. It accepts one String parameter that specifies the value to be used in the Query String passed to the CGI script where it is used to determine the content to display; details for either Environment Variables or Special Folder names.

There are different steps to take depending on whether or not the window is open.

If it is open, then:

Change the search property of the location property of the window object. to the needed Query String. This will make another request for the document with the new Query String.
Move the window into the foreground by calling the focus() method.

If it is not open:

Build a string specifying the features for the new window.
Delete the old object variable (anything allocated using new should be deallocated using delete).
Open the new window and store a reference to it.
Move the window to the foreground by calling focus()

Note: The try {} catch () {} exception handling blocks are features only available in Microsoft's implementation of JavaScript known as JScript used by Internet Explorer. If you want to make this code platform-independent then remove the exception handling blocks.

	function openHelp( s ) {
		try {
			if (wHelp.name != "") { // reload the help script in the open window and focus it.
				wHelp.document.location.search = "?item=" + s;
				wHelp.focus();
			} else {
				var sFeatures = "toolbar=no,location=no,menubar=no,scrollbars=yes,resizeable=yes,status=yes,width=";
				sFeatures += parseInt( (screen.availWidth * 0.75) + "", 10 );
				sFeatures += ",height=" + parseInt( (screen.availHeight* 0.75) + "", 10 );
				delete wHelp;
				wHelp = self.open("../cgi-bin/wsc_help.pl?item=" + s, "WSCHELP", sFeatures);
				wHelp.focus();
			}
		} catch (e) {
			alert("Error opening help window: " + e);
		}
	}

	function closeHelp() {
		if ( wHelp.name != "" ) {
			if ( confirm("do you want to close the help window?") ) {
				wHelp.close();
			}
		}
	}

Manipulating a Separate Window

Some basic introductory information:

Demonstration

Requirements