React Native Input u0026 Form Handling Fundamentals Quiz Quiz

Explore essential concepts for managing user input and forms in React Native. This quiz covers input components, event handling, validation, and best practices to build robust mobile app forms.

1. Basic Input Handling

   Which component is most commonly used for accepting text input from users in React Native?

   1. InputBox
   2. TextInput
   3. TextArea
   4. FormInput

   Explanation: TextInput is the primary component for capturing text input from users in React Native. InputBox and FormInput sound plausible but do not exist in core libraries, while TextArea is used in some other systems but is not standard here. Using the correct component ensures compatibility and expected behavior.

2. Setting Input Values

   What value should you assign to the 'value' prop of a controlled TextInput component if you want to reflect user input changes?

   1. A state variable
   2. A style object
   3. A number variable
   4. A static string

   Explanation: A state variable is commonly used with the 'value' prop to ensure the TextInput's value stays in sync with user actions. A static string would prevent updates, a number variable can cause data type issues, and a style object is intended for styling, not input values.

3. Handling Text Change

   Which event handler is typically used to update state when the text in a TextInput changes?

   1. onSubmit
   2. onChangeText
   3. onClick
   4. onPress

   Explanation: onChangeText is specifically designed to receive the latest text input and update state accordingly. onPress and onClick are used for buttons, not text inputs, while onSubmit is usually for form submission, not real-time updates.

4. Form Submission Logic

   In React Native, which event is commonly handled to detect when a user submits a form by pressing the keyboard's return key?

   1. onPress
   2. onBlur
   3. onSubmitEditing
   4. onFocus

   Explanation: onSubmitEditing is triggered when the return key is pressed, signaling form submission. onBlur is for losing focus, onPress is not related to keyboards for TextInput, and onFocus is for input focus changes.

5. Input Validation

   If you want to enforce a minimum password length after the user leaves a TextInput field, which event handler is best suited for validation?

   1. onScroll
   2. onLayout
   3. onPress
   4. onBlur

   Explanation: onBlur is called when the input loses focus, making it ideal for validating data like password length after editing. onLayout deals with layout info, onPress is for clicks or touches, and onScroll is related to scrolling views.

6. Keyboard Settings

   How would you present a number pad keyboard for numeric input in a React Native TextInput?

   1. Set keyboardMode to 'number-pad'
   2. Set mode to 'decimal'
   3. Set type to 'number'
   4. Set keyboardType to 'numeric'

   Explanation: Setting keyboardType to 'numeric' correctly displays a number pad for numerical input. Using 'type', 'mode', or 'keyboardMode' are not valid props for changing keyboard type in React Native.

7. Secure Inputs

   Which prop enables the hiding of typed characters when entering sensitive information like passwords in TextInput?

   1. privateEntry
   2. maskText
   3. secureTextEntry
   4. hiddenInput

   Explanation: secureTextEntry ensures input characters are masked, enhancing security for sensitive fields. hiddenInput, maskText, and privateEntry do not exist as props and provide no masking by default.

8. Multiple Inputs State Management

   What is a common approach to manage the values of multiple form fields in a simple React Native form?

   1. Use a different component for each field value
   2. Use one state object with keys for each field
   3. Store all values in a separate text file
   4. Use styles to store field data

   Explanation: Using a single state object with keys matching form field names streamlines value management. Using a separate component for each field value or style properties is not suitable, and storing data in a text file is not practical during input handling.

9. Disabling Input

   Which prop can be set on a TextInput to prevent the user from editing its contents?

   1. editable={false}
   2. disabled
   3. locked
   4. readOnly={true}

   Explanation: Setting editable to false disables editing in TextInput. readOnly and disabled are not valid props for TextInput in this context, while locked is not recognized as a standard prop.

10. Placeholders and Hints

    What does setting the 'placeholder' prop on a TextInput in React Native achieve?

    1. It disables autocomplete for the input.
    2. It displays hint text when the field is empty.
    3. It sets the background color of the input.
    4. It saves the previous user entry.

    Explanation: The placeholder prop shows hint text until the user enters something in the input. It does not control background color, store previous entries, or manage autocomplete functionality. Only the first choice directly describes the placeholder behavior.