EPAM Systems Reactjs Developer Interview Questions and Answers

let, var, and const are all used for variable declaration in JavaScript, but they have different scopes and behaviors.

• let has block scope, var has function scope, and const is a constant that cannot be reassigned.

• Using let allows you to declare variables that are limited to the scope of a block statement.

• var variables are hoisted to the top of their function scope.

• const variables must be initialized with a value and ca

React is a JavaScript library for building user interfaces.

• Component-based architecture for reusability

• Virtual DOM for efficient updates

• One-way data binding for predictable data flow

• Supports server-side rendering for SEO optimization

Callback function is a function passed as an argument to another function to be executed later. Hooks are functions that let you use state and other React features without writing a class.

• Callback function is used to handle asynchronous operations or events in JavaScript.

• Example: setTimeout function takes a callback function as an argument to execute after a specified time.

• Hooks are introduced in React 16.8 to allow fu...read more

Box model is a fundamental concept in CSS which defines the spacing and dimensions of an element.

• The box model consists of content, padding, border, and margin.

• Content area is where the actual content of the element is displayed.

• Padding is the space between the content and the border.

• Border surrounds the padding and content.

• Margin is the space outside the border, separating the element from other elements.

• Example: div ...read more