JS WINDOW METHOD EXAMPLE
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<!doctype html>
	<head>
		<title>JS Window Method Examples</title>
	</head>
	<body>
		<h3>Perform various operations on Window object</h3>

        <button onclick="createWindow()">Open a Window</button>
        <button onclick="closewin()">Close the Window</button>
        <button onclick="showAlert()">Show Alert in Window</button>
        
        <script>
        var win;
        // Open window
        function createWindow() {
          win = window.open("", "My Window", "width=500, height=200");
        }
        
        function showAlert() {
            if(win == undefined) {
                // show alret in main window
                window.alert("First create the new window, then show alert in it");
            }
            else {
                win.alert("This is an alert");
            }
        }
        
        // Close window
        function closewin(){
            win.close();
        }
        </script>

	</body>
</html>