In modern web applications and services, code executed on the client side or in custom scripts plays a key role in providing interactivity and user experience. However, even the most well-thought-out code can encounter errors, from network failures to unforeseen exceptions in logic. It is important not only to detect such errors, but also to respond intelligently to them, minimizing negative user experience and improving application stability.
Let’s consider three main strategies of handling user code failures that are widely used in the industry: retry, fallback and alert.
Retry
Retry is an attempt to automatically retry an operation that has failed. This approach is particularly useful for temporary errors, such as network failures or temporary server unavailability.
Real-world examples of retry usage:
- API requests: if a timeout or connection error occurs while accessing the server, the client can retry the request after a small interval of time. Netflix, for example, in its microservices architecture actively uses retry strategies with exponential latency to improve system resilience.
- Asynchronous operations: libraries like Axios or Fetch support retry mechanisms with configurable number of attempts and intervals.
However, it is important to keep a balance – endless repetitions will cause unnecessary load and degrade the user experience. It is common to implement a limit on the number of attempts and intervals with increasing delay (exponential backoff).
Fallback
Fallback is a plan “B” when the main operation fails and the application switches to an alternative solution.
Examples:
- Resource download: if the primary CDN with the library fails to respond, the browser can automatically download a copy from another address.
- Displaying a simplified interface: if a dynamic component fails to load, a simplified version of the page or static content is shown.
- Use of cached data: when the server is unavailable, data is taken from the local cache to provide basic functionality.
Apple, Google and other large companies widely use fallback strategies to ensure smooth operation of their services even in case of server or network problems.
Alert – user notification
When automatic methods can’t completely fix the problem, it’s important to notify the user of the failure in a timely manner and provide recommendations.
Typical alert options are:
- Pop-ups and banners with a message about the problem and possible actions (e.g., “Failed to load data, try refreshing the page”).
- Toast and system notifications that don’t interfere with your work, but inform you of a failure.
- Feedback forms for reporting errors directly to developers.
Proper communication reduces user irritation and helps users understand what’s going on instead of being left in the dark with an idle interface.
An integrated approach
Security and stability best practices advise combining these three strategies:
- First – retry with a limited number of attempts.
- If unsuccessful, switch to fallback.
- At the same time – always alert the user of the current status, especially if critical functionality is unavailable.
This approach is used in many popular services. For example, GitHub repeats connection attempts several times in case of temporary network problems, then shows the user a message about the problems and offers to refresh the page.
Bottom line and recommendations
- Don’t rely on a single method. Use retry, fallback, and alert in conjunction.
- Configure retry with an exponential delay and a limit on the number of attempts.
- Design a fallback that preserves basic functionality and does not degrade the user experience.
- Notify the user informatively but unobtrusively. Make it clear that the application is working on a solution.
- Log all failures and reactions to them to analyze and improve code quality.
The bottom line is that competent handling of user code failures helps you create resilient, reliable applications that remain usable even in the face of unpredictable errors.
