[javascript] How can I close a window with Javascript on Mozilla Firefox 3?

For security reasons, your script cannot close a window/tab that it did not open.

The solution is to present the age prompt at an earlier point in the navigation history. Then, you can choose to allow them to enter your site or not based on their input.

Instead of closing the page that presents the prompt, you can simply say, "Sorry", or perhaps redirect the user to their homepage.