1. What are the features of React?
Major features of React are listed below:
- It uses the virtual DOM instead of the real DOM.
- It uses server-side rendering.
- It follows uni-directional data flow or data binding.
2. List some of the major advantages of React.
Some of the major advantages of React are:
- It increases the application’s performance
- It can be conveniently used on the client as well as server side
- Because of JSX, code’s readability increases
- React is easy to integrate with other frameworks like Meteor, Angular, etc
- Using React, writing UI test cases become extremely easy
3. What are the limitations of React?
Limitations of React are listed below:
- React is just a library, not a full-blown framework
- Its library is very large and takes time to understand
- It can be little difficult for the novice programmers to understand
- Coding gets complex as it uses inline templating and JSX
4. Why can’t browsers read JSX?
Browsers can only read JavaScript objects but JSX in not a regular JavaScript object. Thus to enable a browser to read JSX, first, we need to transform JSX file into a JavaScript object using JSX transformers like Babel and then pass it to the browser.
5. “In React, everything is a component.” Explain.
Components are the building blocks of a React application’s UI. These components split up the entire UI into small independent and reusable pieces. Then it renders each of these components independent of each other without affecting the rest of the UI.
6. What is the purpose of render() in React.
Each React component must have a render() mandatorily. It returns a single React element which is the representation of the native DOM component. If more than one HTML element needs to be rendered, then they must be grouped together inside one enclosing tag such as <form>, <group>,<div> etc. This function must be kept pure i.e., it must return the same result each time it is invoked.
7. What is Props?
Props is the shorthand for Properties in React. They are read-only components which must be kept pure i.e. immutable. They are always passed down from the parent to the child components throughout the application. A child component can never send a prop back to the parent component. This help in maintaining the unidirectional data flow and are generally used to render the dynamically generated data.
8. What is a state in React and how is it used?
States are the heart of React components. States are the source of data and must be kept as simple as possible. Basically, states are the objects which determine components rendering and behavior. They are mutable unlike the props and create dynamic and interactive components. They are accessed via this.state().
9. What are synthetic events in React?
Synthetic events are the objects which act as a cross-browser wrapper around the browser’s native event. They combine the behavior of different browsers into one API. This is done to make sure that the events show consistent properties across different browsers.
10. List some of the cases when you should use Refs.
Following are the cases when refs should be used:
- When you need to manage focus, select text or media playback
- To trigger imperative animations
- Integrate with third-party DOM libraries
11. What are Higher Order Components(HOC)?
Higher Order Component is an advanced way of reusing the component logic. Basically, it’s a pattern that is derived from React’s compositional nature. HOC are custom components which wrap another component within it. They can accept any dynamically provided child component but they won’t modify or copy any behavior from their input components. You can say that HOC are ‘pure’ components.
12. What can you do with HOC?
HOC can be used for many tasks like:
- Code reuse, logic and bootstrap abstraction
- Render High jacking
- State abstraction and manipulation
- Props manipulation
13. What are Pure Components?
Pure components are the simplest and fastest components which can be written. They can replace any component which only has a render(). These components enhance the simplicity of the code and performance of the application.
14. What is Redux?
Redux is one of the most trending libraries for front-end development in today’s marketplace. It is a predictable state container for JavaScript applications and is used for the entire applications state management. Applications developed with Redux are easy to test and can run in different environments showing consistent behavior.
15. What is React Router?
React Router is a powerful routing library built on top of React, which helps in adding new screens and flows to the application. This keeps the URL in sync with data that’s being displayed on the web page. It maintains a standardized structure and behavior and is used for developing single page web applications. React Router has a simple API.
16. Why is switch keyword used in React Router v4?
Although a <div> is used to encapsulate multiple routes inside the Router. The ‘switch’ keyword is used when you want to display only a single route to be rendered amongst the several defined routes. The <switch> tag when in use matches the typed URL with the defined routes in sequential order. When the first match is found, it renders the specified route. Thereby bypassing the remaining routes.
