Detect Browser Window Closure with JavaScript - Quick Guide

Closing a browser window can sometimes be an important event for web developers to track. Thankfully, JavaScript provides a way to detect when a user closes a window. In this quick guide, we'll walk through the steps to detect browser window closure with JavaScript.

Step 1: Attach an event listener to the window object

<script>
    window.addEventListener('beforeunload', function (event) {
        // Code to execute when window is closed
    });
</script>

The window object in JavaScript represents the browser window. We can attach an event listener to this object using the addEventListener() method. In this case, we're using the beforeunload event, which is triggered just before the window is closed.

Step 2: Write code to execute when the window is closed

<script>
    window.addEventListener('beforeunload', function (event) {
        event.preventDefault();
        // Code to execute when window is closed
    });
</script>

When the beforeunload event is triggered, we need to write code to execute. In this example, we've added a call to event.preventDefault() to prevent the browser from closing the window immediately. This gives us time to execute any necessary code before the window is actually closed.

Step 3: Add your own code

<script>
    window.addEventListener('beforeunload', function (event) {
        event.preventDefault();
        // Your own code to execute when window is closed
    });
</script>

Finally, add your own code to execute when the window is closed. This could be anything from saving user data to performing cleanup tasks. Just make sure to test your code thoroughly to ensure it's working as expected.

Conclusion

Detecting browser window closure with JavaScript is a simple process, thanks to the beforeunload event. By attaching an event listener to the window object and writing your own code to execute when the window is closed, you can track this important event and perform any necessary actions.