React, or ReactJS is an open-source front-end development library based on JavaScript. Facebook developed it, and it is now maintained by Meta Inc. and a vibrant community of developers. React uses a component-based architecture that consists of reusable, self-contained units called components, making the development of UI elements easy and efficient for developers.
Being one of the most popular front-end development libraries, React is a must-have skill in a front-end developer's arsenal. Below are some React interview questions and answers that can help you learn more about this front-end technology and prepare to face any interview for ReactJS.
React is a front-end and open-source JavaScript library that is useful for developing user interfaces, especially for applications with a single page. It helps build complex and reusable user interface components of mobile and web applications as it follows the component-based approach.
The important features of React are:
While AngularJS is a popular open-source framework that simplifies web development by creating interactive single-page applications
States and props both are used for handle data in react components but the two have some differences in their functionalities
States: It is used to handle data within a component. It is mutable. We can modify the state data using the setState() function
State is the simplest way to handle and store data in a React application. It allows for the creation of dynamic and responsive user interfaces.
Here are some popular lifecycle methods for enhancing and modifying components' behaviour.
React hooks are simple functions that allow functional components to use state, lifecycle methods, and other React features.
The major commonly used hooks are
Props drilling refers to the process of passing data from a parent component to deeply nested child components. Each component in the hierarchy must pass the props down, even if only the last component in the chain needs the data. This can make the code difficult to maintain and less readable, mainly the application grows larger and more complex.
useContext is the best method to pass data from one component to another component, compared to props drilling. When we need to pass data deeply within the component tree or multiple components need access to the same data (e.g., theme, user authentication status, or localization).
In general, for larger or more complex applications, useContext is often a better choice than props drilling, but for simpler cases, passing props might be fine.
Faster Development:
JSX makes it faster to build and prototype components.
Better Performance:
JSX helps avoid unnecessary DOM Updates, which can lead to improved performance in React JS Applications.
Improved code readability:
JSX helps write code that is easier to understand, especially when working with nested components.
Components are the building blocks of creating User Interfaces(UI) in React. There are two possible ways to create a component.
Function Components: This is the simplest way to create a component. Those are pure JavaScript functions that accept props object as the one and only one parameter and return React elements to render the output:
function Greeting({ message }) {
return <h1>{`Hello, ${message}`}</h1>
}
Class Components: You can also use the ES6 class to define a component. The above function component can be written as a class component:
class Greeting extends React.Component {
render() {
return <h1>{`Hello, ${this.props.message}`}</h1>;
}
}
In React, a side effect is any action like data fetching, or DOM manipulation that occurs in a component that affects something outside the scope of the component's rendering process. In React Js uses useEffect hook to handle side effects within functional components. By using this hook, you tell React that your component needs to do something after render. React will remember the function you passed and call it later after executing the DOM.
Side effects can be categorized based on when and how they are executed:
When using hooks in React JS we need to follow some important rules to avoid bugs.
Higher-order components (HOCs) in React are a pattern used for reusing component logic. A higher-order component is a function that takes a component as input and returns a new component with additional functionality.