Redux is a predictable state container for JavaScript applications, commonly used with React. It simplifies state management and enables scalable applications with a unidirectional data flow.
Last updated on:- 6th June 2023
1.
What is Redux ?
A programming language
A state management library for JavaScript
A database management system
A UI framework
Redux is a state management library for JavaScript applications.
2.
What is the main concept in Redux ?
Actions
Components
Reducers
Selectors
Actions are the main concept in Redux. They represent events that occur in the application.
3.
What is the purpose of an action creator in Redux ?
To define the actions required by an application state
To manage the state of components
To create actions
To handle side effects
Action creators are functions that create actions in Redux.
4.
What is a reducer in Redux ?
A function that handles actions and updates the state
A component that renders the UI
A utility for managing side effects
A tool for debugging Redux applications
Reducers are functions in Redux that handle actions and update the state of the application.
5.
What is the purpose of the Redux store ?
To manage the application's state
To define the structure of the application state
To handle side effects
To manage the routing in the application
The Redux store is responsible for managing the application's state.
6.
What is an action payload in Redux ?
A function that creates actions
The data associated with an action
A utility for managing side effects
A tool for debugging Redux applications
The action payload is the data associated with an action in Redux.
7.
What is the purpose of the Redux devtools ?
To debug Redux applications
To optimize performance
To handle routing
To secure the application
The Redux devtools extension is used for debugging Redux applications, inspecting the state, and tracking actions.
8.
What is the role of middleware in Redux ?
To handle actions and update the state
To manage the application's state
To handle side effects
To define the structure of the application state
Middleware in Redux is used to handle side effects such as asynchronous actions.
9.
What is the purpose of the Redux connect function ?
To connect React components to the Redux store
To connect to a database
To manage API requests
To handle routing
The Redux connect function is used to connect React components to the Redux store, enabling access to the state and actions.
10.
What is the purpose of the Redux combineReducers function ?
To combine multiple reducers into a single reducer
To combine multiple actions into a single action
To combine multiple components into a single component
To combine multiple stores into a single store
The Redux combineReducers function is used to combine multiple reducers into a single reducer function.
11.
What is the purpose of the Redux middleware ?
To handle API requests
To optimize performance
To manage component state in React
To handle asynchronous actions
The Redux thunk middleware allows writing action creators that return functions instead of plain action objects, enabling handling of asynchronous actions.
12.
What is a selector in Redux ?
A component in React
A function that extracts data from the state
A database query
A middleware
A selector is a function in Redux that extracts specific data from the state, often used for computing derived data.
13.
What is the purpose of the Redux action type ?
To handle actions and update the state
To manage the application's state
To define the structure of the application state
To identify the type of an action
The Redux action type is used to identify the type of an action.
14.
What is an action in Redux ?
A component in React
A function that returns an object
A database query
A middleware
In Redux, an action is a plain JavaScript object that represents an intention to change the state.
15.
What is the core principle of Redux ?
Immutability
Encapsulation
Inheritance
Polymorphism
The core principle of Redux is immutability, where state is not directly mutated but new state objects are created.
16.
What is the purpose of the Redux action creator ?
To define the structure of the application state
To manage the application's state
To create actions
To handle side effects
Redux action creators are functions used to create actions.
17.
What is a Redux store enhancer ?
A component in React
A function that extends the store's capabilities
A database table
A middleware
A store enhancer is a higher-order function in Redux that wraps the store to provide additional capabilities, such as middleware support.
18.
What is the difference between actions and action creators in Redux ?
Actions are functions, and action creators are objects
Actions are objects, and action creators are functions
Actions are used to create state, and action creators are used to modify state
Actions are synchronous, and action creators are asynchronous
Actions are plain JavaScript objects that represent an intention to change the state, while action creators are functions that return these action objects.
19.
What are the three principles of Redux ?
Actions, Reducers, Store
Components, Props, State
Dispatch, Subscribe, Middleware
Immutability, Single Source of Truth, Changes with Pure Functions
The three principles of Redux are Immutability, Single Source of Truth, and Changes with Pure Functions.
20.
What is the role of an action in Redux ?
To define the structure of the application state
To handle asynchronous operations
To describe a specific user interaction or event
To update the application state
Actions in Redux describe a specific user interaction or event that triggers a change in the application state.
21.
What is the store in Redux ?
A global object that holds the application state
A component that renders the application UI
A utility function for performing side effects
A middleware for handling asynchronous operations
The store in Redux is a global object that holds the application state and provides methods for dispatching actions and subscribing to state changes.
22.
What is the purpose of mapStateToProps in Redux ?
To define the structure of the application state
To handle asynchronous operations
To connect the state from the store to component props
To update the application state based on actions
mapStateToProps is a function used in Redux to connect the state from the store to the props of a component.
23.
What is the purpose of mapDispatchToProps in Redux ?
To define the structure of the application state
To handle asynchronous operations
To connect the action creators to component props
To update the application state based on actions
mapDispatchToProps is a function used in Redux to connect the action creators to the props of a component.
24.
What is the purpose of the Provider component in Redux ?
To define the structure of the application state
To handle asynchronous operations
To connect a component to the Redux store
To provide access to the Redux store to all components
The Provider component in Redux is used to provide access to the Redux store to all components in the application by wrapping the root component.
25.
What is a middleware in Redux ?
A component that renders the application UI
A utility function for performing side effects
A global object that holds the application state
A function that sits between the action dispatch and the reducer
Middleware in Redux is a function that sits between the action dispatch and the reducer, allowing for additional functionality such as handling asynchronous operations or logging.
26.
What is a dispatch in Redux ?
A function that creates actions
A function that handles asynchronous operations
A function that updates the application state
A function that sends actions to the reducers
A dispatch in Redux is a function that sends actions to the reducers, triggering the state updates based on the action type.
27.
What is the purpose of the getState function in Redux ?
To define the structure of the application state
To handle asynchronous operations
To get the current application state from the store
To update the application state based on actions
The getState function in Redux is used to get the current application state from the store, allowing components or middleware to access the state.
28.
What is the purpose of the action payload in Redux ?
To define the structure of the application state
To handle asynchronous operations
To provide additional data to the reducers
To create memoized selectors for efficient state access
The action payload in Redux is used to provide additional data to the reducers, allowing them to update the state based on the payload values.
29.
What is the purpose of the createSelector function in Redux ?
To define the structure of the application state
To handle asynchronous operations
To combine multiple reducers into a single reducer
To create memoized selectors for efficient state access
The createSelector function in Redux is used to create memoized selectors, which efficiently compute derived state from the Redux store.
30.
What is the purpose of the applyMiddleware function in Redux ?
To define the structure of the application state
To handle asynchronous operations
To combine multiple reducers into a single reducer
To apply middleware to the Redux store
The applyMiddleware function in Redux is used to apply middleware to the Redux store, enabling additional functionality to be added to the dispatch process.