Can You Determine If Chrome Is In Incognito Mode Via A Script

When you're developing a website or web application, you may sometimes need to detect if a user is browsing in Chrome's incognito mode. This can be useful for various reasons, such as tracking user behavior or providing different experiences based on the browsing mode. So, how can you determine if Chrome is in incognito mode using a script?

One common method to check if Chrome is in incognito mode is by looking at the availability of the FileSystem API. Unlike regular browsing mode, Chrome's incognito mode restricts access to certain features, including the FileSystem API. Therefore, by attempting to access this API, we can infer whether the browser is in incognito mode or not.

To achieve this in your code, you can use JavaScript to create a temporary FileSystem object and check for its existence or access permissions. Here's a simple script that demonstrates this technique:

const fs = window.RequestFileSystem || window.webkitRequestFileSystem;

if (fs) {
    fs(window.TEMPORARY, 100, () => {
        console.log('Not in incognito mode');
    }, () => {
        console.log('In incognito mode');
    });
} else {
    console.log('Unable to determine incognito mode');
}

In this script, we first check if the browser supports the FileSystem API by looking for either the `RequestFileSystem` or `webkitRequestFileSystem` method in the global scope. If the API is available, we attempt to create a temporary FileSystem using the `window.TEMPORARY` flag and a size parameter. If the creation is successful, we log that the browser is not in incognito mode. Otherwise, if an error is thrown, we assume the browser is in incognito mode.

It's important to note that browser features and behaviors can change over time, so this method may not be foolproof and could be subject to future updates. Additionally, this approach specifically targets Chrome since the behavior of incognito mode detection can vary across different browsers.

While detecting incognito mode can be beneficial for certain use cases, it's crucial to respect user privacy and browser security settings. Users expect their browsing activities to remain private when using incognito mode, so make sure any detection logic is implemented responsibly and transparently.

In conclusion, identifying whether Chrome is in incognito mode through a script can be achieved by checking the availability of the FileSystem API. While this method provides a helpful way to infer incognito mode status, it's essential to handle such information with care and uphold user privacy standards in your development practices.