Summary of TypeError: Cannot set properties of undefined (setting 'duration')

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    Encountering a Negligible Error in React Form

    The user is experiencing a negligible error in their React form, specifically when adding an answer to an interview application. While the error doesn't prevent the application from functioning correctly, it's causing concern and a desire to address it.

    • The error arises during the process of adding an answer, but despite the error, the data is saved correctly in the application's state.
    • The user reports that the POST request is successful, indicating that the error is not impacting the core functionality of the application.
    • The user wants to understand the root cause of the error and find a way to resolve it, improving the stability and clarity of the application's code.

    Understanding the Error's Impact

    The user's priority is to understand the impact of the error, even if it's minor. They want to ensure that the error doesn't lead to unexpected behavior or inconsistencies in the future.

    • The error's impact on the application's performance is a concern.
    • The user wants to avoid potential issues that might arise from unaddressed errors, even if they seem insignificant at the moment.
    • The error might be a symptom of a deeper problem that could cause more serious issues in the future if left unresolved.

    The Code: Analyzing the React Component

    The provided code snippet reveals a React component responsible for the interview form. It showcases the use of various React libraries and concepts, including state management, form validation, and Redux integration.

    • The component uses the useState hook to manage the state of the form, storing the user's input and other relevant data.
    • The AvForm component is utilized for form validation, providing error messages and validation logic.
    • The component interacts with Redux to manage data persistence and communication between different parts of the application.

    The Error: Identifying the Issue in the JavaScript Logic

    The error arises in the handleSelectedQuestionsChange function, which is responsible for updating the selectedQuestions state with the user's input.

    • The function accesses an array called listOfSelectedQuestions using an index.
    • The error occurs when the item at the specified index doesn't exist, leading to an out-of-bounds exception.

    The Solution: Addressing the Error Using Conditional Logic

    The recommended solution involves using conditional logic to prevent the error by adding an object at the specified index if it doesn't exist.

    • The code checks if the item at the given index in listOfSelectedQuestions exists.
    • If the item exists, it modifies the existing object's property with the user's input.
    • If the item doesn't exist, a new object is created at the index and initialized with the user's input.

    Code Example: Implementing the Solution

    const handleSelectedQuestionsChange = (e, index) => {
      e.preventDefault();
      questionChange(e, index);
      const { name, value } = e.target;
      const listOfSelectedQuestions = [...selectedQuestions];
      if (listOfSelectedQuestions[index]) {
        listOfSelectedQuestions[index][name] = value;
      } else {
        listOfSelectedQuestions[index] = {
          [name]: value
        };
      }
      setSelectedQuestions(listOfSelectedQuestions);
    };

    Preventing Future Errors: Best Practices for React Development

    To avoid similar errors in the future, it's crucial to follow best practices for React development. These include:

    • Robust Error Handling: Implement comprehensive error handling throughout the application using try...catch blocks or error boundary components.
    • Data Validation: Validate user input to ensure it conforms to expected data types and formats.
    • State Management: Use state management libraries or techniques to maintain consistency and prevent unexpected state updates.
    • Code Review and Testing: Thoroughly review and test the code to identify potential issues early in the development process.

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