Engineer Technology Associate

Engineer Technology Associate Interview Questions and Answers

Updated 13 Oct 2023

Q1. How to call api in react

Ans.

To call an API in React, you can use the fetch() method or libraries like Axios.

Use the fetch() method to make HTTP requests in React.
Install Axios library using npm and import it in your React component.
Make API calls in React using Axios by sending GET, POST, PUT, or DELETE requests.
Handle API responses using promises or async/await syntax.

Ans.

Virtual DOM is a lightweight copy of the actual DOM in React, used for efficient updates and rendering.

Virtual DOM is a concept in React where a lightweight copy of the actual DOM is created.
It allows React to efficiently update and render components by comparing the virtual DOM with the actual DOM.
When changes are made to the virtual DOM, React calculates the most efficient way to update the actual DOM.
This helps in improving performance and reducing unnecessary re-renders i...read more

Ans.

React life cycles are methods that are called at different stages of a component's life cycle.

React components have several life cycle methods such as componentDidMount, componentDidUpdate, componentWillUnmount, etc.
These methods allow developers to perform actions at specific points in a component's life cycle.
For example, componentDidMount is called after a component is rendered for the first time, while componentDidUpdate is called after a component's state or props change...read more

Ans.

Asynchronous in JavaScript refers to the ability of the code to run independently of the main program flow.

Asynchronous functions allow other code to run while waiting for a task to complete.
Callbacks, Promises, and Async/Await are common ways to handle asynchronous operations in JavaScript.
Example: setTimeout() function in JavaScript is asynchronous, allowing other code to run while waiting for the timeout to complete.

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Ans.

Mapping in JavaScript involves using the map() method to iterate over an array and transform each element.

Use the map() method to create a new array by applying a function to each element of the original array.
The map() method does not change the original array, it returns a new array with the transformed elements.
Example: const numbers = [1, 2, 3]; const doubledNumbers = numbers.map(num => num * 2);