November 2, 1999 - Is the Window Still Open? | WebReference

November 2, 1999 - Is the Window Still Open?

Yehuda Shiran November 2, 1999
Is the Window Still Open?
Tips: November 1999

Yehuda Shiran, Ph.D.
Doc JavaScript

Every window object has a closed property that contains a Boolean value specifying if the window was closed. Before referring to a browser window, you should make sure it is still open. You can either test the existence of the corresponding window object, or simply use the closed property. Here's an example:

function reloadWin() {
  if (!win.closed) win.location.reload();
var win = open("test.html");
setTimeout("reloadWin()", 60000); // reload after one minute

When a window closes, the window object that represents it continues to exist, and its closed property is set to true. Use closed to determine whether a window that you opened, and to which you still hold a reference (from the return value of the method), is still open. Once a window is closed, you should not attempt to manipulate it, or you will receive a nasty JavaScript error.

For more information, refer to the official documentation from Microsoft and Netscape.