Here are some key aspects and approaches to functional testing of web applications:

• Requirement Analysis: The first step in functional testing is to thoroughly understand the requirements and specifications of the web application. This helps in defining the scope of testing and identifying the expected behaviors and functionalities.
• Test Case Design: Based on the requirements, test cases are designed to cover different functional scenarios. Test cases outline the specific steps to be performed, the expected results, and any test data or prerequisites needed.
• Test Execution: The designed test cases are executed on the web application. Testers interact with the application's user interface, input various data, and validate the output or response received. Testers may use manual testing techniques or automated testing tools to execute the test cases.
• Functional Coverage: Functional testing aims to cover all the major functionalities and features of the web application. This includes testing individual functions, user interfaces, forms, navigation, error handling, data validation, and any specific business rules or workflows.
• Boundary Testing: Boundary testing focuses on testing the application's behavior at the boundary or limits of its functionality. It involves testing inputs at the minimum and maximum allowed values, as well as values just outside those boundaries, to ensure the application handles them correctly.
• Error Handling: Functional testing includes testing the application's error handling capabilities. Testers intentionally trigger errors or invalid inputs to verify that the application detects and handles them appropriately. This includes checking error messages, error logging, and the application's behavior after encountering errors.
• Integration Testing: Functional testing also involves testing the integration between different components or modules of the web application. This ensures that different parts of the application work together seamlessly and produce the desired results.
• Reporting and Defect Tracking: During functional testing, defects or issues encountered are logged and tracked for resolution. Testers document the steps to reproduce the issue, provide supporting information, and communicate them to the development team for fixing.

Functional testing of web applications plays a crucial role in ensuring the quality and reliability of the application. By thoroughly testing its functionality, testers can identify defects, validate user workflows, and ensure that the application meets the intended requirements. It helps in improving user experience, reducing the risk of functional failures, and enhancing the overall quality of the web application.