Frontend Interview Questions Preparation

Can React be used without JSX? How?

🟠 May come up 🎚️ Medium

⚛️ React

What is the difference between an Element and a Component?

🟠 May come up 🎚️ Medium

⚛️ React

What is the difference between functional and class components?

🟡 Often asked 🎚️ Medium

⚛️ React

What is the difference between a library and a framework using React as an example?

🟠 May come up 🎚️ Medium

⚛️ React

What is the difference between Shadow DOM and Virtual DOM?

🟠 May come up 🎚️ Medium

⚛️ React

What is the difference between useEffect and useLayoutEffect?

🟡 Often asked 🎚️ Medium

⚛️ React 🏷️ Hooks

What are Higher-Order Components (HOCs)?

🟠 May come up 🎚️ Medium

⚛️ React

How does React reconciliation work?

🟡 Often asked 🎚️ Medium

⚛️ React

How to create a Promise?

🟡 Often asked 🎚️ Medium

🟨 JavaScript ⏱️ Asynchronicity 🟨 JS Basics

How to prevent unnecessary renders in React?

🟡 Often asked 🎚️ Medium

⚛️ React

How to set the default value of a function?

🟠 May come up 🎚️ Easy

🟨 JavaScript 🟨 JS Basics ⚙️ Functions

How to check if it's an array?

🟠 May come up 🎚️ Easy

🟨 JavaScript 🏷️ Arrays 🟨 JS Basics

How to quickly clear an array?

🟠 May come up 🎚️ Easy

🟨 JavaScript 🏷️ Arrays 🟨 JS Basics

What array creation methods do you know?

🟠 May come up 🎚️ Easy

🟨 JavaScript 🏷️ Arrays 🟨 JS Basics

What array methods do you know?

🟡 Often asked 🎚️ Easy

🟨 JavaScript 🏷️ Arrays 🟨 JS Basics

What is an array and how to work with it?

🟡 Often asked 🎚️ Medium

🟨 JavaScript 🏷️ Arrays 🟨 JS Basics

What are arrow functions and what are their differences?

🟡 Often asked 🎚️ Medium

🟨 JavaScript ⚙️ Functions 🟨 JS Basics

Give examples of binary operators in JavaScript and what are their differences?

🟡 Often asked 🎚️ Medium

🟨 JavaScript 🟨 JS Basics 🏷️ Operators

What is a closure in JavaScript and how does it work?

🟡 Often asked 🎚️ Hard

🟨 JavaScript 🟨 JS Basics

What data types exist in JavaScript?

🟡 Often asked 🎚️ Easy

🟨 JavaScript 🟨 JS Basics

What is the difference between == and === in JavaScript and when is it better to use which operator?

🟢 Almost certain 🎚️ Easy

🟨 JavaScript 🟨 JS Basics 🏷️ Operators

What function declaration methods do you know and what are their differences?

🟡 Often asked 🎚️ Medium

🟨 JavaScript ⚙️ Functions 🟨 JS Basics

What can you pass to a function as a parameter?

🟡 Often asked 🎚️ Easy

🟨 JavaScript ⚙️ Functions 🟨 JS Basics

What are functions for in JavaScript and what problems do they solve?

🟡 Often asked 🎚️ Easy

🟨 JavaScript 🟨 JS Basics ⚙️ Functions

What is hoisting in JavaScript?

🟡 Often asked 🎚️ Medium

🟨 JavaScript 🟨 JS Basics 🏷️ Data types

What are self-invoking functions and why are they needed?

🟠 May come up 🎚️ Hard

🟨 JavaScript ⚙️ Functions

What is the difference between i++ and ++i in JavaScript and what do they return?

🟡 Often asked 🎚️ Easy

🟨 JavaScript 🟨 JS Basics 🏷️ Operators

Have you heard about the nullish coalescing operator (??) ? Can you tell me about it?

🟡 Often asked 🎚️ Easy

🟨 JavaScript 🟨 JS Basics 🏷️ Operators

How to convert a value to number in JavaScript?

🟡 Often asked 🎚️ Medium

🟨 JavaScript 🟨 JS Basics 🏷️ Data Types

What can be object keys and values in JavaScript?

🟡 Often asked 🎚️ Easy

🟨 JavaScript 🏷️ Objects

What methods does an object have in JavaScript?

🟠 May come up 🎚️ Medium

🟨 JavaScript 🏷️ Objects 🟨 JS Basics

What is a pure function in JavaScript?

🟡 Often asked 🎚️ Easy

🟨 JavaScript 🟨 JS Basics ⚙️ Functions

How to convert a value to string in JavaScript?

🟡 Often asked 🎚️ Medium

🟨 JavaScript 🟨 JS Basics 🏷️ Strings

What string methods do you know?

🟡 Often asked 🎚️ Medium

🟨 JavaScript 🏷️ Strings 🟨 JS Basics

How does the switch operator work in JavaScript and how does comparison happen?

🟡 Often asked 🎚️ Easy

🟨 JavaScript 🟨 JS Basics 🏷️ Conditional

What is the ternary operator and how does it work in JavaScript?

🟠 May come up 🎚️ Easy

🟨 JavaScript 🟨 JS Basics 🏷️ Conditional

What does the typeof operator do and in what format does it return data?

🔴 Rarely asked 🎚️ Easy

🟨 JavaScript 🟨 JS Basics

What are the different ways to declare variables in JavaScript and what are their differences?

🟢 Almost certain 🎚️ Easy

🟨 JavaScript 🟨 JS Basics 🏷️ Data Types

What are the pros and cons of using React?

🟠 May come up 🎚️ Medium

⚛️ React

Do you have any questions for us?

🟢 Almost certain 🎚️ Hard

🌱 soft-skills

What is forwardRef and why is it needed?

🟠 May come up 🎚️ Medium

⚛️ React

What is React.lazy() and what is it used for?

🟡 Often asked 🎚️ Hard

⚛️ React

How to properly use React.lazy() with Suspense?

🟡 Often asked 🎚️ Hard

⚛️ React

What are your salary expectations?

🟢 Almost certain 🎚️ Hard

🌱 soft-skills

Tell me about yourself

🟢 Almost certain 🎚️ Hard

🌱 soft-skills

What are the top 10 libraries you've used when building React applications?

🟠 May come up 🎚️ Medium

⚛️ React

What does useCallback do and how does it differ from useMemo?

🟡 Often asked 🎚️ Medium

⚛️ React 🏷️ Hooks

What architectural patterns do you know, and what are their features?

🟠 May come up 🎚️ Hard

🏷️ Theory

What are controlled and uncontrolled components?

🟠 May come up 🎚️ Medium

⚛️ React

What design patterns do you know, and what are their features?

🟠 May come up 🎚️ Hard

🏷️ Theory

What are the principles of Functional Programming?

🟠 May come up 🎚️ Hard

🏷️ FP 🏷️ Theory

What are fragments (<>...</>)? Why is it better to use fragment instead of an extra div?

🟠 May come up 🎚️ Medium

⚛️ React

What is the key in lists for? What will happen if you use an array index as a key?

🟡 Often asked 🎚️ Medium

⚛️ React

What types of loops in JavaScript do you know, and what are their differences?

🟠 May come up 🎚️ Easy

🟨 JavaScript 🏷️ Loops 🟨 JS Basics

What are the principles of OOP?

🟠 May come up 🎚️ Hard

🏷️ OOP 🏷️ Theory

What are portals (Portals) in React?

🟠 May come up 🎚️ Medium

⚛️ React 🏷️ Portals

What are props and why are props immutable?

🟠 May come up 🎚️ Medium

⚛️ React

What are "pure" components (Pure Components)?

🟠 May come up 🎚️ Medium

⚛️ React

What are spread and rest operators?

🟡 Often asked 🎚️ Medium

🟨 JavaScript 🟨 JS Basics 🏷️ Objects 🏷️ Arrays

What are Synthetic Events in React?

🟠 May come up 🎚️ Medium

⚛️ React

Describe the main phases of the React component lifecycle and the corresponding methods for class and functional components

🟢 Almost certain 🎚️ Hard

⚛️ React

What are the rules for using hooks in React?

🟡 Often asked 🎚️ Medium

⚛️ React 🏷️ Hooks

What are the main factors that cause React components to re-render?

🟡 Often asked 🎚️ Medium

⚛️ React

What do .then(), .catch(), .finally() methods return?

🟡 Often asked 🎚️ Medium

🟨 JavaScript ⏱️ Asynchronicity 🟨 JS Basics

What does useEffect do? When does an effect without dependencies trigger? What is the dependency array for?

🟢 Almost certain 🎚️ Easy

⚛️ React 🏷️ Hooks

What happens after we enter a URL in the browser bar?

🟠 May come up 🎚️ Hard

🏷️ Theory

What is asynchronous code execution?

🟡 Often asked 🎚️ Medium

🟨 JavaScript ⏱️ Asynchronicity 🟨 JS Basics

What is conditional rendering in React?

🟢 Almost certain 🎚️ Easy

⚛️ React 🏷️ Rendering

What is destructuring and how does it work?

🟠 May come up 🎚️ Medium

🟨 JavaScript 🟨 JS Basics 🏷️ Arrays 🏷️ Objects

What is JSX and why is it needed?

🟠 May come up 🎚️ Easy

⚛️ React

What is NaN, what is its type, and how to check for it?

🟠 May come up 🎚️ Easy

🟨 JavaScript 🏷️ Data Types 🟨 JS Basics

What is an object?

🟡 Often asked 🎚️ Easy

🟨 JavaScript 🟨 JS Basics 🏷️ Objects

What is Promise.all() used for

🟠 May come up 🎚️ Medium

🟨 JavaScript ⏱️ Asynchronicity 🟨 JS Basics

What is Promise and why is it needed?

🟡 Often asked 🎚️ Medium

🟨 JavaScript ⏱️ Asynchronicity 🟨 JS Basics

What is React and what problems does it solve?

🟢 Almost certain 🎚️ Medium

⚛️ React

What is React Fiber? What is the main goal of React Fiber?

🟡 Often asked 🎚️ Hard

⚛️ React

What is React.memo, how does it work, where is it applied and for what purpose?

🟡 Often asked 🎚️ Medium

⚛️ React

What is setInterval, what is it for, and how does it work?

🟠 May come up 🎚️ Easy

🟨 JavaScript ⏱️ Asynchronicity 🟨 JS Basics

What is setTimeout, what is it for, and how does it work?

🟡 Often asked 🎚️ Easy

🟨 JavaScript ⏱️ Asynchronicity 🟨 JS Basics

Tell us about the useCallback hook, how it works, where it's applied and for what purpose?

🟠 May come up 🎚️ Medium

⚛️ React 🏷️ Hooks

Tell us about the useContext hook, how it works, where it's applied and for what purpose? When is it better to use it, and when is it better to refuse?

🟠 May come up 🎚️ Medium

⚛️ React 🏷️ Hooks

Tell us about the useId hook, how it works, where it's applied and for what purpose?

🔴 Rarely asked 🎚️ Medium

⚛️ React 🏷️ Hooks

Tell us about the useMemo hook, how it works, where it's applied and for what purpose?

🟡 Often asked 🎚️ Medium

⚛️ React 🏷️ Hooks

Tell us about the useOptimistic hook, how it works, where it's applied and for what purpose?

🟠 May come up 🎚️ Medium

⚛️ React 🏷️ Hooks

Tell us about the useRef hook, how it works, where it is used and what for?

🟡 Often asked 🎚️ Medium

⚛️ React 🏷️ Hooks

Tell us about the useState, how does it work, where is it applied and what is it for?

🟠 May come up 🎚️ Easy

⚛️ React 🏷️ Hooks

Tell us about the useTransition hook, how it works, where it's applied and for what purpose?

🟡 Often asked 🎚️ Medium

⚛️ React 🏷️ Hooks

What is Virtual DOM?

🟢 Almost certain 🎚️ Medium

⚛️ React

What React Hooks do you know?

🟢 Almost certain 🎚️ Medium

⚛️ React 🏷️ Hooks

When is it appropriate to use class components today?

🟠 May come up 🎚️ Medium

⚛️ React

Which array methods mutate and which don't?

🟠 May come up 🎚️ Medium

🟨 JavaScript 🏷️ Arrays 🟨 JS Basics

Why are you changing jobs?

🟢 Almost certain 🎚️ Hard

🌱 soft-skills

Tell me about your work processes

🟢 Almost certain 🎚️ Hard

🌱 soft-skills

Frontend Interview Questions

🔧 Filters and search

Can React be used without JSX? How?

What is the difference between an Element and a Component?

What is the difference between functional and class components?

What is the difference between a library and a framework using React as an example?

What is the difference between Shadow DOM and Virtual DOM?

What is the difference between useEffect and useLayoutEffect?

What are Higher-Order Components (HOCs)?

How does React reconciliation work?

How to create a Promise?

How to prevent unnecessary renders in React?

How to set the default value of a function?

How to check if it's an array?

How to quickly clear an array?

What array creation methods do you know?

What array methods do you know?

What is an array and how to work with it?

What are arrow functions and what are their differences?

Give examples of binary operators in JavaScript and what are their differences?

What is a closure in JavaScript and how does it work?

What data types exist in JavaScript?

What is the difference between == and === in JavaScript and when is it better to use which operator?

What function declaration methods do you know and what are their differences?

What can you pass to a function as a parameter?

What are functions for in JavaScript and what problems do they solve?

What is hoisting in JavaScript?

What are self-invoking functions and why are they needed?

What is the difference between i++ and ++i in JavaScript and what do they return?

Have you heard about the nullish coalescing operator (??) ? Can you tell me about it?

How to convert a value to number in JavaScript?

What can be object keys and values in JavaScript?

What methods does an object have in JavaScript?

What is a pure function in JavaScript?

How to convert a value to string in JavaScript?

What string methods do you know?

How does the switch operator work in JavaScript and how does comparison happen?

What is the ternary operator and how does it work in JavaScript?

What does the typeof operator do and in what format does it return data?

What are the different ways to declare variables in JavaScript and what are their differences?

What are the pros and cons of using React?

Do you have any questions for us?

What is forwardRef and why is it needed?

What is React.lazy() and what is it used for?

How to properly use React.lazy() with Suspense?

What are your salary expectations?

Tell me about yourself

What are the top 10 libraries you've used when building React applications?

What does useCallback do and how does it differ from useMemo?

What architectural patterns do you know, and what are their features?

What are controlled and uncontrolled components?

What design patterns do you know, and what are their features?

What are the principles of Functional Programming?

What are fragments (<>...</>)? Why is it better to use fragment instead of an extra div?

What is the key in lists for? What will happen if you use an array index as a key?

What types of loops in JavaScript do you know, and what are their differences?

What are the principles of OOP?

What are portals (Portals) in React?

What are props and why are props immutable?

What are "pure" components (Pure Components)?

What are spread and rest operators?

What are Synthetic Events in React?

Describe the main phases of the React component lifecycle and the corresponding methods for class and functional components

What are the rules for using hooks in React?

What are the main factors that cause React components to re-render?

What do .then(), .catch(), .finally() methods return?

What does useEffect do? When does an effect without dependencies trigger? What is the dependency array for?

What happens after we enter a URL in the browser bar?

What is asynchronous code execution?

What is conditional rendering in React?

What is destructuring and how does it work?

What is JSX and why is it needed?

What is NaN, what is its type, and how to check for it?

What is an object?

What is Promise.all() used for

What is Promise and why is it needed?

What is React and what problems does it solve?

What is React Fiber? What is the main goal of React Fiber?

What is React.memo, how does it work, where is it applied and for what purpose?

What is setInterval, what is it for, and how does it work?