A method and system to display a pop-up window when a user leaves a website are disclosed. A user accesses a website with a web browser. When a web page from the website is loaded into the user's browser, a client-side variable is set to a particular value, such as the current time. When the web page from the website is unloaded from the browser, a hidden pop-up window is loaded. The hidden pop-up window is programmed to sleep and then check the value of the client-side variable. A change in the value of the client-side variable indicates a new web page from the same web server has been loaded into the web browser and the user has not left the website. However, if a web page from a different web server is loaded into the browser, then the value of the client-side variable remains unchanged. Consequently, when the hidden pop-up window awakes and checks the value of the client-side variable, the pop-up window can determine whether the user has left the original website. If the user has left the original website, the pop-up window is displayed. If not, the pop-up window is unloaded before ever being displayed to the user.