Non-standard file extensions used for the web app manifest file

The importance of having a .webmanifest extension for the application manifest file lies in the standards and best practices for Progressive Web Apps (PWAs).

The Web App Manifest is a JSON file that provides information about a web application in a format that a web browser can understand. It’s used to describe the web application, including its name, icons, and other details that are necessary for a native app-like experience.

Using the .webmanifest extension for the file is recommended because:

• It clearly indicates the file’s purpose and format, making it easier for developers and tools to identify and work with the file.
• It follows the standard convention for web manifests, as specified by the W3C Manifest specification.
• Some browsers and tools may expect or require the .webmanifest extension to properly recognize and process the file.

Your file e.g. manifest.json is still a valid JSON file and may work as expected, but renaming it to have a .webmanifest extension (e.g., manifest.webmanifest) would bring it in line with the recommended standard, making it more consistent with other PWAs and potentially avoiding any issues with browser or tool compatibility.

What does it mean that browsers and tools may expect or require the .webmanifest extension to properly recognize and process the file?

When a browser or tool expects or requires the .webmanifest extension, it means that they are designed to look for a file with this specific extension to function correctly. Here are some possible scenarios where this might be relevant:

• Browser support: some browsers might only recognize and process a web manifest file if it has the .webmanifest extension. If the file has a different extension, such as .json, the browser might not be able to find or use it, which could prevent the web application from being installed or functioning as a Progressive Web App.
• Service worker registration: service workers are a key component of PWAs, and they often rely on the web manifest file to register and install the service worker. If the web manifest file doesn’t have the correct extension, the service worker registration process might fail, which could prevent the web application from working offline or receiving push notifications.
• Development tools and libraries: some development tools and libraries, such as those used for building, testing, and debugging PWAs, might expect the web manifest file to have the .webmanifest extension. If the file has a different extension, these tools might not be able to find or process it correctly, which could lead to errors or unexpected behavior.
• SEO and search engine indexing: search engines like Google might also use the web manifest file to discover and index PWAs. If the file doesn’t have the correct extension, it’s possible that search engines might not be able to find or index the web application correctly, which could affect its visibility and discoverability.

It’s worth noting that the specific requirements and behaviors of browsers and tools can vary, and not all of them might require the .webmanifest extension. However, using the recommended extension can help ensure compatibility and avoid potential issues, making it a good practice to follow the standard convention for web manifests.

Rule

• Audit: Quality
• Standard: SiteLint.
• Level: Best Practices.
• ID: manifest-extension