100+ Frontend Developer Intern Interview Questions and Answers

To start a frontend project without a UI, I would gather requirements, sketch ideas, and create a prototype for user feedback.

• 1. Gather Requirements: Understand the purpose and target audience of the application.

• 2. Research: Look for inspiration from similar applications or design systems.

• 3. Sketch Ideas: Create rough sketches or wireframes to visualize layout and components.

• 4. Create a Prototype: Use tools like Figma or Adobe XD to build an interactive prototype.

• 5. Get Feedb...read more

Temporal Dead Zone is a behavior in JavaScript where variables are not accessible before they are declared.

• Temporal Dead Zone occurs when accessing variables before they are declared

• Variables in the Temporal Dead Zone cannot be accessed or assigned

• The Temporal Dead Zone is a result of JavaScript's hoisting behavior

• Example: accessing a variable before it is declared will throw a ReferenceError

React JS is a popular JavaScript library for building user interfaces.

• Component-based architecture

• Virtual DOM for efficient updates

• JSX syntax for writing components

• One-way data binding

• Reusable components

• React Native for mobile app development

JavaScript has 7 different data types including number, string, boolean, null, undefined, object, and symbol.

• Number: represents numeric values

• String: represents textual values

• Boolean: represents true/false values

• Null: represents intentional absence of any object value

• Undefined: represents an uninitialized value

• Object: represents a collection of properties

• Symbol: represents a unique identifier

Design a signin page using HTML and CSS only

• Create a form element with input fields for username and password

• Style the form using CSS to make it visually appealing

• Add a submit button for users to sign in

• Consider adding error messages or validation for user input

• Use CSS to make the page responsive for different screen sizes

CSS Grid is a layout system that allows for easy creation of complex and responsive web designs.

• CSS Grid allows for the creation of complex layouts with rows and columns

• It provides a more flexible and efficient way to design web layouts compared to traditional methods

• It allows for responsive design without the need for media queries

• It can be used in combination with other CSS layout systems like Flexbox

• Example: Using CSS Grid to create a responsive image gallery

Virtual DOM is a lightweight copy of the actual DOM that allows efficient updates and rendering in JavaScript frameworks.

• Virtual DOM is a concept used in JavaScript frameworks like React.

• It is a lightweight copy of the actual DOM tree.

• Changes made to the virtual DOM are compared with the actual DOM to determine the minimal updates needed.

• This helps in efficient rendering and improves performance.

• Virtual DOM allows developers to write code as if the entire page is rendered on ...read more

Hybrid mode refers to a combination of remote and in-office work, common in early stage startups.

• Hybrid mode allows for flexibility in work location, combining the benefits of remote work with in-person collaboration.

• Working in early stage startups can be exciting and fast-paced, with opportunities to take on diverse responsibilities and make a significant impact.

• It is important to be adaptable and willing to wear multiple hats in a startup environment.

• Communication skills ar...read more

Your company specializes in innovative web solutions, leveraging modern technologies to enhance user experience and engagement.

• The company focuses on responsive design, ensuring applications work seamlessly across devices.

• Utilizes frameworks like React or Angular for building dynamic user interfaces.

• Emphasizes performance optimization, possibly using tools like Webpack or Lighthouse.

• Incorporates RESTful APIs for efficient data handling and integration.

• Prioritizes user experie...read more

Inheritance allows a class to inherit properties and methods from another class, while polymorphism allows objects to be treated as instances of their parent class. Encapsulation restricts access to certain components of an object.

• Inheritance: Child classes can inherit properties and methods from parent classes.

• Polymorphism: Objects can be treated as instances of their parent class.

• Encapsulation: Restricts access to certain components of an object.

Hoisting is a JavaScript behavior where variable and function declarations are moved to the top of their containing scope.

• Hoisting applies to both variable and function declarations.

• Variable declarations are hoisted but not their initializations.

• Function declarations are fully hoisted, including their definitions.

• Hoisting can lead to unexpected behavior if not understood properly.

Access in Redux can be defined by creating actions and reducers to manage state changes.

• Define action types to represent different types of access (e.g. READ, WRITE, DELETE)

• Create action creators to dispatch actions for defining access

• Write reducers to update the state based on the dispatched actions

• Use selectors to access the defined access in components

Flexbox is for one-dimensional layouts, while Grid is for two-dimensional layouts, each serving different design needs.

• Flexbox is ideal for aligning items in a single row or column, e.g., navigation bars.

• Grid is better for complex layouts with both rows and columns, e.g., web page layouts.

• Flexbox allows for flexible item sizes, while Grid provides fixed areas for items.

• Use Flexbox for simpler, linear designs and Grid for more structured, grid-based designs.

IIFE stands for Immediately Invoked Function Expression. It is a JavaScript function that is executed as soon as it is defined.

• IIFE is a way to create a function expression and immediately invoke it.

• It helps in creating a private scope for variables and functions.

• It is commonly used to avoid polluting the global namespace.

• IIFE can be written using different syntaxes like using parentheses, function declaration, or arrow functions.

Adding small features like responsive design, clear navigation, consistent branding, and interactive elements can make a website look more professional.

• Implement responsive design to ensure the website looks good on all devices

• Ensure clear and intuitive navigation for easy user experience

• Maintain consistent branding elements such as colors, fonts, and logos

• Incorporate interactive elements like animations, hover effects, or microinteractions

Redux Toolkit is an official, opinionated, batteries-included toolset for efficient Redux development.

• Official toolset for Redux

• Opinionated and batteries-included

• Helps with common Redux tasks like store setup, reducer logic, and actions

Design a restaurant website with menu, reservation system, and location map.

• Include high-quality images of the restaurant, food, and ambiance

• Create a user-friendly navigation menu for easy access to different sections

• Implement a reservation system with date, time, and party size options

• Integrate a location map with directions and contact information

• Ensure mobile responsiveness for easy access on different devices

The difference between == and === in JavaScript is that == compares only the values, while === compares both values and types.

• The == operator compares two variables by converting them to the same type before making the comparison.

• The === operator compares two variables without type conversion, so they must be of the same type to be considered equal.

• Example: 1 == '1' will return true, but 1 === '1' will return false.

On-page SEO refers to optimizing elements on a website to improve search engine rankings, while off-page SEO involves external factors like backlinks and social signals.

• On-page SEO includes optimizing meta tags, headings, content, and images on a website.

• Off-page SEO involves building backlinks from other websites, social media shares, and online reputation management.

• Examples of on-page SEO techniques are keyword optimization, internal linking, and mobile responsiveness.

• Exam...read more

The purpose of the FLEX property in CSS Flexbox is to define how a flex item will grow or shrink to fit the available space.

• The FLEX property is used to set the initial size of a flex item.

• It can be used to specify how much a flex item can grow or shrink relative to the other flex items.

• The FLEX property is a shorthand for the FLEX-GROW, FLEX-SHRINK, and FLEX-BASIS properties.

Controlled components manage form data via state, while uncontrolled components handle data directly from the DOM.

• Controlled components use React state to manage form inputs, e.g., <input value={this.state.value} onChange={this.handleChange} />.

• Uncontrolled components store their own state internally, e.g., <input defaultValue='initial' ref={input => this.input = input} />.

• Controlled components provide a single source of truth, making it easier to manage and validate form dat...read more

Doc type in HTML specifies the version of HTML being used in the document.

• Doc type declaration is placed at the very beginning of an HTML document before the <html> tag.

• It is written as <!DOCTYPE html> for HTML5.

• The doc type declaration helps the browser to render the web page correctly.

• It is not an HTML tag but an instruction to the web browser about what version of HTML the page is written in.

Yes, I use Redux Toolkit for state management in my frontend projects.

• I use Redux Toolkit to simplify the process of managing state in my applications.

• It provides a set of tools and best practices for managing state in a predictable way.

• I find it helpful for handling complex state logic and data flow in my projects.

useQuery is for fetching data from the server, useMutation is for making changes to the server data.

• useQuery is used for fetching data from the server, while useMutation is used for making changes to the server data.

• useQuery is read-only and does not modify data on the server, while useMutation is used for updating, creating, or deleting data on the server.

• useQuery is typically used for GET requests, while useMutation is used for POST, PUT, DELETE requests.

• Example: useQuery c...read more

React Query is used for managing server state and caching data in React applications.

• Provides a powerful and flexible way to fetch, cache, and update data from APIs

• Automatically handles caching, background refetching, and stale data management

• Improves performance by reducing unnecessary network requests

• Simplifies data fetching and updating logic in React components

To display 20 stars in a grid of 5 lines with 4 stars each, we can use simple loops or string manipulation in programming.

• Use a loop to print stars: for (let i = 0; i < 5; i++) { console.log('****'); }

• Alternatively, create a single string: let stars = '**** **** **** **** ****'; console.log(stars);

• In HTML, you can use <pre> tags to maintain formatting: <pre>**** **** **** **** ****</pre>

• Using CSS, you can style the stars: <div style='font-family: monospace;'>****<br>****<br>*...read more

The tag is used to break the paragraph.

• The
  tag is a self-closing tag.

• It is used to insert a line break within a paragraph.

• It does not require a closing tag.