Top 75+ Frontend Developer Interview Questions and Answers [2023 Updated] (2023)

Table of Contents
Front End Developer Interview Questions for Freshmen 1. What are meta tags in HTML? 2. Name some basic design elements 3. Was ist Load-Balancing? 4. What does npm stand for? 5. What is Scope in JavaScript? 6. How are JavaScript and jQuery different? 7. What is a content security policy? 8. Was ist Cross-Site-Scripting (XSS)? 9. What is user-centric design? 10. What is Callback Hell? 11. What is polymorphism? 12. What is strict mode? 13. What is meant by the KISS principle? 14. What does SOLID stand for? 15. What is clickjacking? 16. What is coercion in JavaScript? 17. What is IIFEs? 18. What is a grid system in CSS? 19. What is Mixin? 20. Mention ways to reduce page load time? Front-end developer interview questions for the experienced 1. What is Stringify? 2. Specify the elements of the CSS box model. 4. What is the advantage of Srcset? 5. Was ist MySQL? 6. What is MongoDB? Git-Interviewfragen 1. What is a "version control system"? 2. Distinguish between centralized and distributed version control system 3. Explain Git Push and Git Pull 4. Name some Git commands and functions 5. Explain the difference between Git Pull and Git Fetch 6. What is a merge conflict in Git and how to resolve it? 7. What is Git Stash? 8. Distinguish between Git merge and Git rebase HTML-Interviewfragen 1. What is an attribute in HTML? 2. Was ist Marquee in HTML? 3. What is Semantic HTML? How does it work? 4. How do you display a table on an HTML web page? 5. What is SVG to HTML? 6. How do you separate a section of text in HTML? 7. How do you create nested web pages in HTML? 8. Distinguish between ordered list and unordered list CSS-Interviewfragen 1. What is the best way to incorporate CSS styling into HTML? 2. Name the different types of CSS selectors 3. What are Sass, Less and Stylus? 4. Explain the box sizing property 5. What are the ways to hide an element with CSS? 6. What does "Important" mean in CSS? 7. Was sind CSS-Sprites? 8. What property is used to underline, strikethrough, and overline text? JavaScript-Interviewfragen 1. What are the different data types in JavaScript? 2. Was ist Callback in JavaScript? 3. What is the difference between function declaration and function expression? 4. What do you mean by cookies in JavaScript? 5. Was sind Closures in JavaScript? 6. What are imports and exports in JavaScript? 7. What is the difference between Undefined, Undeclared and Null in JavaScript? 8. What is the best way to remove duplicates from a JavaScript array? ReactJS Interview Questions 1. What is JSX? 2. What is Virtual DOM? 3. What are React Extensions? Name some of them. 4. What is an event in React? How do you create one? 5. What are components in ReactJS? 6. What is a state in response? How do you implement it? 7. What is higher order and pure components in reaction? 8. How do you implement React Routing? Angular interview questions 1. What is data binding and how does it work? What data binding methods does Angular use? 2. What is typescript? 3. What is AoT compilation? How is it different from JiT? 4. What are pipes in Angular? Explain its types 5. What are Promises and Observables in Angular? 6. What are form controls and form groups? 7. What is eager and lazy loading? 8. Was ist String-Interpolation in Angular? General interview questions 1. What are the advantages of TypeScript over JavaScript? 2. How is a web developer different from a web designer? 3. What is backend development? 4. What is CoffeeScript? 5. How would you ensure that a web design is user friendly? 6. Would you recommend a web designer role or a web developer role? 7. How would you increase page performance? Next Steps Videos

Frontend developers are in demand today. Many companies willingly hire them with attractive salary packages. If you think you have the skills to become a frontend developer and want to make it a career, then you've come to the right place. This interview questions tutorial for frontend developers will help you crack your next interview. This Frontend Developer Interview Questions tutorial has compiled questions about different languages ​​and frameworks used for frontend development.

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Front End Developer Interview Questions for Freshmen

1. What are meta tags in HTML?

  • Meta tags are the tags that are inserted into the head tag of the HTML page
  • Meta tags are not important for the interface, but for the browser.
  • Meta tags are always contained in name or value pairs
  • Meta tags consist of character encoding, title or even description.

2. Name some basic design elements

Some of the basic elements of the design are

  • Line - a line mark created with any pen or brush, or even an edge created when two shapes meet
  • Size - it is the area that one shape takes with the other
  • Texture - the surface of the mold - smooth, soft, hard, shiny, and so on
  • Color - The light reflected from objects. The three characteristics of color are hue, value, and intensity.

3. Was ist Load-Balancing?

Load balancing is the distribution of all incoming network traffic across all backend servers.

4. What does npm stand for?

Npm stands for Node Package Manager.

5. What is Scope in JavaScript?

In JavaScript, each function has its own scope. It's basically a collection of rules for accessing variables and variables themselves.

6. How are JavaScript and jQuery different?

JQuery is a library built using the JavaScript language, and JavaScript is the language itself.

7. What is a content security policy?

Content Security Policy, also known as CSP, is a header in HTML that gives site operators complete control over the resources loaded on the site.

8. Was ist Cross-Site-Scripting (XSS)?

XSS, Cross-Site Scripting is an attack that takes place when an attacker uses a web application to send malicious code to another user in the form of a browser-side script.

9. What is user-centric design?

User-centered designs are those designs that the designer is solely focused on and which are guided by the needs of the users and them at every stage of the design.

10. What is Callback Hell?

JavaScript that uses callbacks and is intuitively hard to find. The recalls stacked in the form of a pyramid structure.

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11. What is polymorphism?

The word polymorphism means having many different shapes. When we speak in object-oriented terms, polymorphism refers to an interface, multiple functions.

12. What is strict mode?

A new feature of ECMAScript 5 is strict mode, which allows you to place a function or program in a "strict" operational context.

13. What is meant by the KISS principle?

KISS, a backronym of "Keep it simple, stupid". This was the US Navy's main design in 1960. The KISS principle states that the simpler the system, the better it works.

14. What does SOLID stand for?

S.O.L.I.D is an acronym for Object-Oriented Design Principles

S-principle of individual responsibility

Ö-open-close principle

L-Liskov Substitutionsprinzip

I-Principle of interface separation

D-dependency.

15. What is clickjacking?

ClickJacking is an attack where the developer tricks users into believing they are clicking one thing, but are actually clicking the other.

16. What is coercion in JavaScript?

The conversion of two different built-in JavaScript types is called coercion. It comes in two forms, explicit and implicit.

17. What is IIFEs?

IIFEs stands for Instant Invoked Function Expression. This is executed immediately after creation.

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18. What is a grid system in CSS?

A structure that allows content to be placed in a consistent and manageable manner, both horizontally and vertically. There are two key components of the grid system; rows and columns.

19. What is Mixin?

A mixin is a block of code that enables the set of CSS declarations that we can reuse on our website.

20. Mention ways to reduce page load time?

The best way to decrease page load time is

  • image optimization
  • Browser-Cache
  • Compress and optimize content

Front-end developer interview questions for the experienced

1. What is Stringify?

Stringify is used to convert a JavaScript object to a string.

2. Specify the elements of the CSS box model.

The CSS box model consists of 4 elements

  • contents
  • upholstery
  • Border
  • Rand

4. What is the advantage of Srcset?

When we want to generate many new solutions from exact images on multiple devices, Srcset is used. This helps improve the user interface.

5. Was ist MySQL?

MySQL is a relational database management system that uses SQL as the default language to manage its database. Just like other databases, MySQL uses a table-like structure.

6. What is MongoDB?

MongoDb is a NoSQL database that displays the data items with a JSON-like structure. To make changes in MongoDB, the programmer must use the MongoBD Query Language.

Git-Interviewfragen

1. What is a "version control system"?

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AVersion Control System (VCS)is a program that records all changes made to a file or record so that a previous version can be restored if necessary. This ensures that everyone on the team is working on the most current version of the file.

2. Distinguish between centralized and distributed version control system

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In a centralized version control system:

  • It stores all file versions on a central server.
  • No developer has a full copy of the local system files.
  • If the project's central server fails, you will lose all of the project's data.

In a distributed version control system:

  • Every developer has a copy of all code versions on their computer.
  • Improves the ability to work offline and eliminates the need for a single backup location.
  • Even if the server crashes, there is no danger.

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3. Explain Git Push and Git Pull

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Git push is a commandthat pushes the contents of a local repository to a remote repository. It pushes after changing a local repository to share the changes with remote team members.

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Git Pull is a commandwhich fetches changes from a remote repository and merges them into the local repository. It consists of two commands: git fetch followed by git merge.

4. Name some Git commands and functions

  • Git Config - Configure the username and email address
  • Git init - Initializes a local Git repository
  • Git Add - Add one or more files to the staging area
  • Git Diff - View the changes made to the file
  • Git Commit - Commit changes to the header but not to the remote repository
  • Git reset - Revert local changes to the state of a Git repo
  • Git Status - Displays the status of the working directory and staging area
  • Git Merge - Merge a branch into an active branch
  • Git Push - Upload content from the local repository to a remote repository
  • Git Pull - Get and download content from a remote repository

Also read:How to become a frontend developer

5. Explain the difference between Git Pull and Git Fetch

Git-Fetch

  • It only downloads new data from a remote repository using Git-Fetch
  • It does not include any of this new information in your working files
  • To update the remote tracking branches, run Git fetch at any time
  • Command - get git origin

git fetch – all

Git-Pull

  • Git fetches new data and integrates it into the current working files, updating the current HEAD branch with the latest changes from the remote server
  • It attempts to combine remote changes with those made locally
  • Command - git pull origin master

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6. What is a merge conflict in Git and how to resolve it?

If you are merging branches with opposite commits, amerge conflictoccurs, and Git needs your help to choose which changes to include in the final merge.

Resolve with the GitHub Conflict Editor

When competing for row changes, i. H. when users make different changes to the same line of the same file in different branches in your git repository, this is done to avoid merge conflicts.

Step 1: Under your repository name, click Pull Requests.

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Step 2: In the Pull Requests list, click the pull request that has the merge conflict that you want to resolve. At the end of your pull request, click Resolve Conflicts.

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Step 3: Decide whether you want to keep only the changes from your branch, only the changes from the other branch, or make a completely new change that includes the changes from both branches.

Step 4: Clear the conflict markers and make desired changes in the final merge.

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Step 5: If your file has a merge conflict, scroll down to the next set of conflict marks and repeat steps four and five to resolve the issue. Mark the file as resolved once you have resolved all conflicts.

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Step 6: If you have more than one conflicting file, go to the left side of the screen and select the next file you want to edit under Conflicting Files. Then repeat the above steps until you resolve all merge conflicts in your pull request.

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Step 7: Click Apply Merge once you have resolved all the merge conflicts. This will merge the entire base branch into your head branch. Click Merge Pull Request to combine your pull requests.

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Fix the issue with a local clone of the repository and push the update to your GitHub branch.

All other forms of merge conflicts are resolved using this method. To push the update, you can use the command line or a program like GitHub Desktop.

Step 1: Open Git Bash. Go to the local Git repository where the merge conflict exists.

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Step 2: Make a list of the files affected by the merger dispute. In this case, there is a merge conflict in the styleguide.md file.

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Step 3: Navigate to the merge conflict file in any text editor like Sublime Text or Atom. Look for the conflict marker "<<<<<<" if you want to see where the merge conflict started in your file.

After the line "<<<<<<HEAD" you will see the changes from the base branch.

Step 4: Next you will see ======= what separates your changes from the changes in the other branch followed by >>>>>>> BRANCH-NAME

Step 5: Decide whether you want to simplify your branch's changes, only the other branch's changes, or make a completely new change that includes the changes from both branches.

Step 6: Delete the conflict markers <<<<<, =====, >>>>> and make desired changes in the final merge.

Step 7: Add or deploy your changes. Confirm your changes with a comment.

You can now combine the branches from the command line or upload your changes to yoursGitHub-Remote-Repositoryand merge them into one pull request.

Also read:Git-Rebase vs. Merge

7. What is Git Stash?

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8. Distinguish between Git merge and Git rebase

Suppose you are working on a new feature in a dedicated branch and another team member is pushing new commits to the master branch.

merge

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Merge is used to merge new commits into your feature branch. Each time you need to merge changes, an additional merge commit is required. It spoils the history of your feature branch.

A fox

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You can rebase the feature branch into the master instead of merging it. This includes all new commits in the master branch. It also rewrites the project history by creating brand new commits for every commit in the original branch.

This brings us to the end of the Git questions. These are some of the top front-end interview questions related to version control.

HTML-Interviewfragen

HTML is an integral partof frontend development. The following frontend developer interview questions are based on HTML.

1. What is an attribute in HTML?

<h1>Hello</h1>

<p>Welcome</p>

<br>

<h2>Click the subscribe button</h2>

<button>Subscribe</button>

  • Attributes are the properties that can be added to oneHTML-Tagthat change the behavior or display of the tag.
  • It adds attributes right after the HTML tag name in the brackets.

2. Was ist Marquee in HTML?

  • The marquee is used to scroll the text on the web page.
  • The image or text will automatically scroll up, down, left, or right.
  • You must use <marquee> tags to apply for a marquee.

3. What is Semantic HTML? How does it work?

  • Semantic HTML is a type ofencoding.
  • It is the use of HTML markup to emphasize the semantics or meaning of the content.
  • Consider the following scenario: The <b></b> tag is not used for bold statements in semantic HTML, while the <i></i> element is used for italics.
  • Instead, use the <em></em> and <strong></strong> tags.

Also read:An Ultimate Guide to Coding 2022

4. How do you display a table on an HTML web page?

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  • To display data in a tabular format, use the table> HTML tag.
  • It is also used to control the layout of the page, e.g. B. the header, the navigation bar, the main content and the footer.

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5. What is SVG to HTML?

<svg width="100" height="100">

<circle cx="50" cy="50" r="40" stroke="yellow" stroke-width="4" fill="red" />

</svg>

  • HTML SVG is a markup language that describes vector and raster graphics. XML text files define SVG images and associated behaviors.
  • It is typically used for X, Y coordinate system charts such as pie charts and two-dimensional charts.

6. How do you separate a section of text in HTML?

In HTML, you use the following tags to break up a section of text:

<br> tag - It is a character used to break a line of text. It transfers the flow of text to a new line by wrapping the existing line.

<p> Tag - This tag is used to create a paragraph of text.

<blockquote> This tag is used to display large quoted passages.

7. How do you create nested web pages in HTML?

<!DOCTYPE html>

<html>

<body>

<h2>Example of HTML iframes</h2>

<p>

Specify the size of the iframe using the height and width attributes:

</p>

<iframe src="https://simplilearn.com/" height="600" width="800"></iframe>

</body>

</html>

  • You refer to a web page within a web page as a nested web page.
  • HTML's built-in iframe tag lets you create nested web pages.

8. Distinguish between ordered list and unordered list

<!DOCTYPE html>

<html>

<body>

<h2>HTML-Listenbeispiel</h2>

<ul>

<li>Kaffee</li>

<li>Tee</li>

<li>Milch</li>

</ul>

<ol>

<li>Kaffee</li>

<li>Tee</li>

<li>Milch</li>

</ol>

</body>

</html>

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  • An unordered list uses <ul> </ul> tags and each element of the list is written between <li> </li> tags.
  • An ordered list uses <ol> </ol> tags and each element of the list is written between <li> </li> tags.

Now that we're familiar with HTML questions, let's look at the next set of frontend developer interview questions, CSS

CSS-Interviewfragen

1. What is the best way to incorporate CSS styling into HTML?

There are three methods of incorporationCSS in HTML:

  • You use inlineCSSwhen only a single element needs to be styled or when little styling is needed.
  • External style sheet: When a style is applied to many elements or HTML pages, it uses an external style sheet.
  • Internal style sheet: An internal style sheet is used when a single HTML document has a unique style and numerous elements.

Also read:11 secrets about CSS that you can't miss

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2. Name the different types of CSS selectors

//universal selector

* {

Color green";

Font size: 20px;

line height: 25px;

}

//Element type selector

ul {

line type: none;

Rand: solide 1px #ccc;

}

// ID-Selector

#Container {

Width: 960px;

Edge: 0 automatic;

}

<div id="container"></div>

//class selector

.Crate {

Padding: 10px;

Rand: 10px;

Width: 240px;

}

<div class="box"></div>

// Descendant combinator

#container .box {

Swimmer: left;

padding below: 15px;

}

<div id="container">

<div class="box"></div>

<div class="box-2"></div>

</div>

<div class="box"></div>

//child combinator

#container> .box {

Swimmer: left;

padding below: 15px;

}

<div id="container">

<div class="box"></div>

<div>

<div class="box"></div>

</div>

</div>

// Generic sibling combiner

h2 ~ p {

Margin Bottom: 20px;

}

<h2>Title</h2>

<p>Paragraph example.</p>

<div class="box">

<p>Paragraph example.</p>

</div>

//Attributeselector

input[type="text"] {

background color: #444;

Width: 200px;

}

<input type="text">

3. What are Sass, Less and Stylus?

Sass - Sass is short for "Syntactically Awesome Style Sheets". It is usually preceded by a "$" sign.

$font color: #fff

$bg color: #00f
#Crate

Color: $FontColor

Background: $bg color

Less - LESS is an acronym for "Leaner Style Sheets". Less uses "@" to define the variables.

@fontcolor: #fff;

@bg-color: #00f

#Crate{

color: @fontcolor;

background: @bg color;

}

Stylus - Stylus offers great flexibility in writing syntax. It doesn't use @ or $ to define variables.

font color = #fff;

bg-color = #00f;
#Crate {

color: font color;

background: bg color; }

4. Explain the box sizing property

The box size property defines how the height and width of a box are calculated.

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Content box - The default width and height apply only to the content of the element. Padding and frame are added outside the box.

Padding Box - You add the dimensions to both the content and the padding of the element. It adds the frame outside the box.

Border Box - The dimensions are added to the content, fill and border.

5. What are the ways to hide an element with CSS?

Display: none

Hides the content and does not store it in the DOM

Visibility: hidden

It adds the element to the DOM and takes up space. However, it is not visible to the user

Position: absolut

You can make the element appear off-screen

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6. What does "Important" mean in CSS?

The keyword "important" specifies the highest priority and overrides the cascaded property.

p {

Colour blue! important;

}

#Matter {

Color green;

}


<p id="thing">Will be BLUE.</p>

7. Was sind CSS-Sprites?

  • Since each image sends an HTTP request separately, a web page with a large number of photos takes longer to load.
  • CSS sprites are used to minimize the loading time of a web page by combining multiple small images into a single image.
  • It reduces the number of HTTP requests and therefore the time it takes to load pages.

8. What property is used to underline, strikethrough, and overline text?

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text style

text type

text decoration

Text-Transformation

JavaScript-Interviewfragen

JavaScript is usedto add user interaction to an application. The following section addresses the frequently asked interview questions for JavaScript frontend developers.

1. What are the different data types in JavaScript?

JavaScript has many data types to provide the basic functionality required for a web application. They are mentioned in this table.

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2. Was ist Callback in JavaScript?

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A callback is a JavaScript function that is sent to another function as an argument or parameter.

You call this function whenever the function for which it is provided is called.

3. What is the difference between function declaration and function expression?

function declaration

function abc(){

return 5;

}

Within the main JavaScript code, this is declared as a separate statement. It is possible to call it before the function has been defined. It provides improved code readability.

functional expression

var a = function abc(){

return

}

It is constructed within an expression or other construct. It is generally used when a conditional declaration of a function is required.

4. What do you mean by cookies in JavaScript?

A cookie is a small piece of data that is sent from a website and stored on the user's computer by the web browser used to access the page.

Cookies are used to store information for later use and to track browsing activity on a website.

The simplest approach to create a cookie using JavaScript is as follows:

document.cookie = "key1 = value1; key2 = value2; expires = date";

To delete a cookie, you can simply set an expiry date and time; It is recommended to specify the correct path of the cookie.

function delete_cookie(name) {

document.cookie = name + "=; Path=/; Expires=Do, 01 Jan 1970 00:00:01 GMT;";

}

5. Was sind Closures in JavaScript?

Closures in JavaScript are a function where an inner function has access to the outer function's variables.

function outer_function()

{

Varb = 10;

function inner_func(){

var a = 20;

Konsole.log(a+b);

}

return inside;

}

A closure has three scope chains –

  • Has access to the variable defined in the curly braces that represents its scope.
  • Has access to outer function variables.
  • Has the ability to access global variables.

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6. What are imports and exports in JavaScript?

Export

export const sqrt = Math.sqrt;

export function square(x) {

return x * x;

}

export function diag(x, y) {

return sqrt(Quadrat(x) + Quadrat(y));

}

This file exports two functions that calculate the squares or diagonals of the input.

Import

import { square, diag } from "calc";

console.log (Quadrat (4)); // 16

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console.log(diag(4, 3)); // 5

This is where you import these functions and pass input to these functions to calculate square and diagonal.

7. What is the difference between Undefined, Undeclared and Null in JavaScript?

there are x

console.log(x) //Undefinierte Variable

var y=NULL

console.log(y) //Null-Variable

console.log(z) //Undeclared variable

Undefined - Undefined means that a variable has been declared, but a value has not yet been assigned to that variable.

Null - Null is an assignment value that you can assign to any variable that you don't want to hold a value.

Undeclared - Variables that are undeclared or do not exist in a program or application.

8. What is the best way to remove duplicates from a JavaScript array?

You can delete duplicates of aJavaScript-Arrayin one of two ways:

By using the filter technique - Three arguments are required to call the filter() function. These are the array, the current element, and the current element index.

The For Loop is used to store all repeated elements in an empty array.

ReactJS Interview Questions

React is a popular frontendJavaScript library. It is important to have a good understanding of a JavaScript framework or library for app development.

The following segment of frontend developer interview questions includes React questions.

1. What is JSX?

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  • JSX is a syntactic JavaScript extension. It's a term used in React to describe how the user interface should look.
  • You can write HTML structures in the same file as JavaScript code using JSX.
  • By avoiding the use of complicated JS DOM structures, JSX makes the code easier to understand and debug.

2. What is Virtual DOM?

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  • DieVirtual DOMis the lightweight version of Real DOM that React keeps in memory.
  • Since Real DOM processing does not draw anything on the screen, it is much slower than virtual DOM processing.
  • When the status of an object changes, Virtual DOM only updates that object in the real DOM and not all.

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3. What are React Extensions? Name some of them.

  • React is more than just a UI framework; It includes a number of extensions that cover the entire application architecture.
  • It has server-side rendering capability.
  • Supports mobile app creation.
  • Among other things, Flux and Redux have been added.

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  • Flux is Facebook's application architecture for developing online applications.
  • With React Native you can build mobile apps entirely in JavaScript.

4. What is an event in React? How do you create one?

Top 75+ Frontend Developer Interview Questions and Answers [2023 Updated] (36)

An event is an action triggered by the user or any system event, such as pressing a key, mouse button, etc.

5. What are components in ReactJS?

Top 75+ Frontend Developer Interview Questions and Answers [2023 Updated] (37)

Components are the building blocks of a React application that represent part of the user interface.

  • A component that is used in one area of ​​the application can be reused in another area. This helps speed up the development process.
  • A component can contain several other components.
  • A component must define a rendering method that specifies how the component is rendered in its minimal form in the DOM.
  • A component can also receive props. These are properties passed from its parent to specify values.

6. What is a state in response? How do you implement it?

A state is an object that stores the values ​​of properties belonging to a component that can change over time.

Top 75+ Frontend Developer Interview Questions and Answers [2023 Updated] (38)

Here are some characteristics of a state -

  • You can change a status as a result of user action or changes in the network.
  • React re-renders the component in the browser when an object's state changes.
  • You initialize the state object in the constructor.
  • It can store multiple properties in the state object.
  • this.setState() is used to change the value of the state object.
  • The setState() function merges the new and old states and the previous state into a flat merge.

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7. What is higher order and pure components in reaction?

higher order components

  • A higher-order component is a function that takes a component and returns a new component.
  • It facilitates the reuse of component logic.

const NewComponent = HigherOrderComponent(OriginalComponent)

Pure Components

  • React.Component is the base class for React components. React.PureComponent is a variation of the React.Component class and performs flat comparison of props and states.
  • A React component can be considered pure if it renders the same output for the same state and props.

8. How do you implement React Routing?

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Given that you have App, About, and Contact components, routing can be implemented using the code shown above.

Angular interview questions

If you are well versedangle frame, then these Angular frontend developer interview questions will be helpful.

Also read:How to learn Angular: Angular benefits and certifications

1. What is data binding and how does it work? What data binding methods does Angular use?

Data binding is a method of manipulating web page elements through the use of a web browser. It is used in interactive elements such as forms, calculators, tutorials, and games on web pages.

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Bidirectional data binding is used by Angular. Any changes made to the UI will reflect the elements in the model state and vice versa.

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2. What is typescript?

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TypeScript is an object-oriented programming language that is a superset of JavaScript. Put simply, it's JavaScript with a number of other notable capabilities. All TypeScript code is finally compiled to JavaScript.

  • TypeScript supports all JavaScript libraries and frameworks, just to name a few key features. Angular is a single-page application framework written in JavaScript.
  • As code complexity increased, JavaScript had to meet the criteria of OOP, which led to the development of TypeScript.
  • TypeScript helps create faster code, which improves performance.

3. What is AoT compilation? How is it different from JiT?

Ahead of Time (AOT), compilation translates your code as it's built, not when it's downloaded and run by the browser. This guarantees that the browser renders content quickly. Include the —aot option with the ng build or ng serve commands to specify AOT compilation.

The just-in-time (JIT) compilation technique converts computer code into machine code while it is being executed or executed. Dynamic compilation is another name for it. When using the ng build or ng serve CLI commands, JIT compilation is used by default.

4. What are pipes in Angular? Explain its types

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Pipes are simple functionswhich take an input value, process it and, in a more technical sense, return a modified value as an output. Angular has several built-in tubes. However, they can manufacture custom tubing to meet your specific needs.

Below are some key features:

  1. The pipe "|" Symbol is used to define pipes.
  2. Pipes can be linked together in a chain.
  3. The colon (:) can be used to provide arguments to pipes.

Pure whistles

These are pure function pipes. As a result, a pure pipe uses no internal state, and the output remains constant as long as the parameters provided remain constant. When Angular detects a change in the given arguments, it calls the pipe. A single instance of the pure pipe is used in all components.

Unclean pipes

Angular calls an impure pipe for each change detection cycle, regardless of the change in the input fields. Multiple pipe instances are created for these pipes. The inputs to these pipes can be changed.

All pipes are clean by default. On the other hand, the clean attribute can be used to identify unclean pipes as shown below.

@Rohr({

Name: 'Demopipe',

pure : true/false

})

export class DemopipePipe implements PipeTransform {

5. What are Promises and Observables in Angular?

While both concepts in Angular deal with asynchronous events, promises deal with one by one while observables deal with a time sequence of events.

  • Promises are objects that return only one value at a time. They take effect as soon as they are created and cannot be stopped. They are promises to push the child failure.
  • Observables – Observables are only executed when the scribe() method is used to subscribe to them. They output multiple values ​​over a period of time. They help perform tasks such as forEach, filter, and retry, among others. Subscribers receive error messages due to their actions. The listener stops receiving new data when it executes the unsubscribe() method.

6. What are form controls and form groups?

form control

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  • It allows validation through the Form Control class.
  • It creates a new instance of this class for each input field.
  • With these instances, you can check the field's values ​​to see if they've been touched, untouched, or soiled.

form group

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  • A group of controls is represented by the FormGroup class.
  • Several control groups are possible in one form.
  • If all controls are valid, the Form Group returns True.
  • It also contains a list of all validation issues.

7. What is eager and lazy loading?

Eager Loading - The default approach to module loading is eager loading. Eager loading function modules are loaded before the program starts. Usually you reserve this for applications that aren't too big.

Lazy Loading – If necessary, lazy loading loads the function modules dynamically. This speeds up the application. It is used in larger applications where not all modules are required from the start.

8. Was ist String-Interpolation in Angular?

String interpolation is a one-way data-binding method that delivers data from TypeScript code to an HTML view. Double curly brackets are used to indicate this. This template expression allows the data from the component to be displayed in the view.

{{ Data }}

General interview questions

Not all questions are nuclear. The interviewer also wants to understand your opinion on specific frontend related questions or suggestions. The final segment of the Frontend Developer Interview Questions article focuses on some common questions.

1. What are the advantages of TypeScript over JavaScript?

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  • TypeScript flags compilation errors during development.
  • Supports strongly-typed and static typing.
  • Better features like interfaces, generics and more.
  • Offers excellent tool support with IntelliSense.

2. How is a web developer different from a web designer?

web developer

web designer

Build web applications using languages ​​such as HTML, CSS, and JavaScript

Design web applications using tools like Adobe Photoshop, Sketch

They often use JavaScript frameworks for streamlined development

They often use Adobe Creative Cloud for most design needs

It requires good programming skills

It requires good graphic design skills

You need to keep up to date with the latest web frameworks and libraries

You need to keep up to date with the latest design trends and color palettes

3. What is backend development?

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Web development that takes place on the back end of programs is precisely called back-end development. Backend development includes server-side web application logic and integration, as well as activities like writing APIs, building libraries, and working with system components instead of frontend development that focuses on customer-facing services and programs. Backend developers create code that allows a database and an application to talk to each other. Backend developers are responsible for the backend of a website, which includes servers, databases, and apps, and they control what you don't see.

Also read:How to become a backend developer

4. What is CoffeeScript?

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  • CoffeeScript is a JavaScript compilationProgramming language.
  • It's an attempt to directly demonstrate the positive aspects of JavaScript.
  • It also makes JavaScript code development easier by providing a more consistent syntax and avoiding the peculiarities of the JavaScript language.

5. How would you ensure that a web design is user friendly?

  • A frontend developer should work closely with the user experience team to visualize the design for the app.
  • You should also test the web application and take user input.
  • The app developed should be compatible with different platforms and ultimately run smoothly on the cell phone.

6. Would you recommend a web designer role or a web developer role?

It's really a matter of preference.

  • If you are inclined towards the creative aspect, you should opt for a role as a web/UX designer.
  • If you are more inclined towards the coding aspect, you should go for the web developer role.

7. How would you increase page performance?

Top 75+ Frontend Developer Interview Questions and Answers [2023 Updated] (50)

  • You should clean up the HTML document
  • External HTTP requests could be minimized
  • Sprites, compressed images, and smaller images can be included
  • Paste the JavaScript at the bottom of the page
  • Optimize CSS, JavaScript and HTML
  • Caching und CDN
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