Top 60 Web Developer Interview Questions and Answers in 2021

Web developers usually create and design websites. They are responsible for the look and finish of the site. They are also held responsible for the site’s technical aspects, like its capacity and performance, which are important measures of any website’s speed and how much traffic the site will handle.

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Is Web developer a good career?

Yes, we can say web development is a good career. According to recent research, “Web Developer” was the most in-demand job in tech and one of the top-paying jobs too. As stated by the U.S. Bureau of Labor, the job market for Web Developer is expected to grow 15 percent by 2026.

If you are searching for a “Web developer Interview Questions and Answers,” then you are on the right page. Make sure you go through all the Web Developer Interview Questions.

Top Web Developer Interview Questions and Answers

1. List the key responsibilities of a Web Developer?


  1. Command on  HTML, CSS, PHP, JavaScript, and other relevant web design coding languages
  2. They should know to create and test applications for websites.
  3. Collaborate
  4. Present design specs.
  5. Work with graphics and other designers.
  6. Troubleshoot website problems if there are any.
  7. Maintain and update the websites.
  8. Monitor the website traffic.
  9. Stay up-to-date on technology.

2. List the four different types of pseudo-classes?

A pseudo-class in CSS can be defined as a keyword that is added to a selector that will specify a special state of the selected element. For example, The hover is used to change the button’s color whenever the user’s pointer hovers over it.

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The four different types of pseudo-classes are:

  1. Dynamic: These pseudo-classes are applied to any element to define how they are shown whenever the cursor is located on them, or when we click on them, or whenever they are selected.
  2. Links: These classes are used to style a link in its normal state by default and when it has already visited.
  3. Structural: These pseudo-classes will allow us to style elements that are based on an exact numerical position of an element.
  4. Others: Some elements are styled differently based on their language or type of label.

3. Differentiate between SOAP and REST?

SOAP means Simple Object Access Protocol.REST means Representational State Transfer.
It is a protocol.It is an architectural pattern.
It works with XML formats.It can work with plain text, XML, HTML, and JSON.
SOAP cannot make use of REST.REST can make use of SOAP.

4. What languages should the web developers know?

  1. HTML
  2. CSS
  3. SQL
  4. PHP/Ruby/Python
  5. JQuery
  6. JavaScript

5. Define Namespacing in JavaScript?

Namespacing can be defined as a technique that is employed to avoid collisions with other variables or objects in a global namespace. JavaScript doesn’t really have built-in support for namespaces as other languages, and it has objects and closures that are used to achieve a similar effect.

6. Name the newly introduced input types in HTML5?

  1. color
  2. date
  3. Datetime-local
  4. email
  5. month
  6. number range

7. What is CORS? 

Cross-Origin Resource Sharing (CORS) can be defined as an HTTP-header-based technique that will allow a server to indicate any other origins such as domain, scheme, or port than its own, from where a browser will permit loading of resources. For some security reasons, browsers restrict the cross-origin HTTP requests that are initiated from scripts.

8. How to reduce page loading time?

Tips to reduce:

  1. Check for the Current Speed of the Website. 
  2. Optimize the Images. 
  3. Don’t Scale Down the Images. 
  4. Compress and Optimize the Content.
  5. Put Stylesheet References at Top.
  6. Put Script References at Bottom. 
  7. Place JavaScript and CSS in External Files. 
  8. Minimize HTTP Requests.

9. Name the form elements that support media content in HTML5?

  1. <audio>
  2. <video>
  3. <source>
  4. <embed>
  5. <track>

10. Mention some advantages of HTTP/2 as compared with HTTP 1.1?


  1. Improvement of web positioning
  2. HTTP headers data compression
  3. Prioritization of request
  4. Less broadband consumption

Web Developer Interview Questions and Answers

11. List the new form elements introduced in HTML5?

  1. <keygen> – It is used to generates an encryption key.
  2. <output> – It is used to define the result of an expression.
  3. <datalist> – It will specify a list of options for input controls.
  4. <progress> – It will head in the direction of 100% of the max value.
  5. <meter> – It provides for a gauge, displaying the general value within a range.

12. Define SVG and why is it used?

SVG means scalable vector graphics, and it is defined as a file format that will allow us to display vector images on the website. Meaning that we can scale an SVG image up and down as required without losing any of its quality and making it a great choice for a responsive web design.

13. Define an ETag and how does it work?

The ETag or an entity tag is part of the HTTP, which is the protocol for the World Wide Web(WWW). It is one of several techniques that an HTTP provides for a Web cache validation, That will allow a client to make conditional requests. An ETag is an opaque identifier that is assigned by the Web server to a specific version of a resource that is found at a URL.

14. Differentiate between Canvas and SVG?

Canvas usually draws 2D graphics on the fly (with JavaScript).It is a language for describing 2D graphics in XML.
Resolution dependent.Resolution Independent.
It has poor text rendering capabilities.It is suited for applications with huge rendering areas (Google Maps)

15. Why do we use Canvas in HTML?

<canvas> can be defined as an HTML element mainly used to draw graphics through scripting (usually JavaScript). It can be used to draw graphs, combine photos, or create simple animations.

16. Explain Long polling?

Long polling can be defined as a mechanism where the server will elect to hold a client’s connection open for long as possible and delivering a response only after the data becomes available.

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17. Is there any default border size of a Canvas?

There is no default border size of a Canvas. You have to adjust using the CSS.

18. Differentiate between localStorage and sessionStorage objects?

Here, the data is not deleted upon the closure of a window.Here, the object is deleted immediately upon closing a window.

19. Explain what DTD is?

A DTD (Document Type Definition (DTD) ) defines the structure, legal elements and attributes of the XML document.

20. Differentiate between IDs and Classes?

Each element must have only one IDWe use the same class on multiple elements.
They are uniqueThey are not unique.
Each page must only one element with that ID.We can use multiple classes on the same element.

21. Differentiate between CDATA and PCDATA in DTD?

It is an Unparsed Character Data, and the CDATA is used about text data that shouldn’t be parsed by the XML parser.It is a Parsed Character Data. XML parsers will parse all the text in the XML document.

22. Name some of the new features that are introduced in CSS3?

  1. Rounded corners
  2. Animation
  3. Custom layout
  4. Media queries

23. Differentiate between cookies and local storage?

CookiesLocal Storage
They have an expiration, and the cookie data get deleted after some timeThere is no expiration concept, and they should be removed manually.
Here, the data accessible both at the client-side and server-side.  The data will be sent to the serverside with every cookie request.Here, Only the local browser-side data is accessible.  The server cannot use local storage until it sends a request to the server via POST or GET.

24. Name the new APIs provided by HTML5?

  1. Constraint validation API
  2. History API
  3. Media API
  4. Text track API
  5. Application cache API
  6. Data transfer API
  7. User interaction API
  8. Command API

25. Define Responsive Web Design (RWD) in HTML and CSS?

Web pages are usually viewed using many various devices: desktops, tablets, and phones. It is known as responsive web design when we use HTML and CSS to resize, shrink, hide, enlarge, or move the content in order to make it look good on any screen.

26. What tag is used for a multi-line text input control in HTML?

For multi-line text input control,  We can use the “textarea tag.”

27. Differentiate between null value and undefined value?

NULL ValueUndefined Value
Null is an assignment value. There is no value here. Not even zeroUndefined indicates that we have declared a variable been but has not yet been assigned a value.

28. Can you list some of the types of CSS that are used?

  1. External CSS:  These are used to import an external CSS file into the HTML document.
  2. Inline CSS: It supports the addition of CSS inline, along with HTML elements.
  3. Embedded CSS: It is mainly used to add the  CSS styles by using the <style> attribute.

29. How to refer to the CSS file on the web page?

We refer to the .CSS file in the webpage by making  use of the <link> tag.  It should be placed between <head></head>tag. Example <linkhref=”/css/mystyle.css” type=”text/css” rel=”stylesheet”/>

30. Name the different types of pop-up boxes available in JavaScript?

  1. Prompt – It will pop up a dialog box that asks the user to input followed confirmation buttons.
  2. Alert – It will just display a message with an OK button.
  3. Confirm – It will pop up a confirmation message window with the Cancel and OK buttons.

Web Developer Interview Questions and Answers

31. Why do we use a selector in CSS?

We use a CSS selector with a rule in the inline elements that may require styling. With selectors, it is easy for us to find and select HTML elements that are based on factors, like name, ID, attribute, etc.

32. Differentiate between <div> and <frame>?

These divisions serve local content the same as the frames, but that content is not independent of the page.The frames can load other resources by using HTML.
<div> tag represents a division or a section in a HTML document.Frames allow us to show more than one HTML document in the same browser window.

33. Define Scope in JavaScript? List the different types of Scopes?

Scope in JavaScript is usually referred to as the current context of code, which then determines the accessibility of variables to JavaScript. 

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The two types of scope are local and global: 

Global variables: They are declared outside of a block.

Local variables: They are declared inside of a block.

34. Define grouping in CSS3?

IN CSS3, Grouping is used to give the user the ability to reuse and apply the same CSS style element to various HTML entities by using one single declaration statement.

35. Differentiate between XHTML  and HTML?

XHTML means Extensible Markup LanguageHTML means Hypertext Markup Language.
Dynamic web pages are XHTML.A static webpage is an HTML web page.
XHTML is based on XML.HTML is based on SGML.

36. Differentiate between ‘==’ and ‘===’ operators?

‘==’ operator checks for the valueThe ‘===’ operator checks for both the value and the type.

37. Why do we use WebKit in CSS3?

WebKit can be defined as a  web browser engine that is used by browsers like Safari and Chrome. We can make use of WebKit features like animation, transition, transform, and more through the use of the -WebKit prefix in the CSS.

Some of the engines for browsers are:

  1. Presto for Opera
  2. Edge for Internet Explorer

38. Name few web development tools?

  1. CodeKit to combine, minify, and syntax-check in JavaScript.
  2. JS to structure a web application and develop a single-page application
  3. GitHub to work with a team on a particular project
  4. CodePen to deploy websites and build test cases.
  5. Grunt to automate repetitive tasks.

39. Tell me something about HTTP/3?

Web Developer Interview Questions - HTTP/3

HTTP/3 can be defined as a major revision of the (HTTP) Hypertext Transfer Protocol, and It is a technology that underpins the transfer of data on the web. HTTP/3 runs over QUIC – It is an encrypted general-purpose transport protocol that will multiplex various streams of data on one single connection. 

40. How to link images and files on the web? 

There are two ways of linking files and images on the Web:

  1. Absolute links have the full URL, and all directory information is encoded in the link.
  2. Relative links relate where the current page is to where the image or document is located.

41. Define Child Selectors in CSS?

Child Selector is mainly used to match all elements that are  “child” of a given element. It usually gives the relation between two elements. The element > element selector will select those elements that are the children of a specific parent.

Web Developer Interview Questions and Answers

42. Name the various HTTP request types supported in Restful Web Services?

Restful web services usually support HTTP request types such as GET, POST, PUT, and DELETE.

DELETE is used to remove the resource from the server. 

Put is used to update an existing entity. 

GET retrieves data from the server. 

POST is usually used for creating a new entity, and it is used to upload a file or submit a completed web form.

43. What is Pagination? 


Pagination can be used in almost every web application to divide the returned data and display it on various pages within a single web page. Pagination includes the logic of preparing and displaying the links to the different pages. Pagination is handled client-side or server-side.

44. Define Type Coercion in JavaScript?

Type Coercion is referred to as the technique of automatic or implicit conversion of values from one data type to another data type. It also includes conversion from Number to String, Boolean to Number, String to Number,  etc., when various types of operators are applied to the values.

45. Can you name the  <border-radius> property attributes for four corners?

  1. <border-top-left-radius>
  2. <border-top-right-radius>
  3. <border-bottom-left-radius>
  4. <border-bottom-right-radius>

46. Define Webpack?

The Webpack can be defined as an open-source JavaScript module bundler. Webpack will take the dependencies and will generate a dependency graph that allows the web developers to use a modular approach for web application development purposes. It is also used from the command line, or it can be configured by using a config file named webpack.

47. List the components of the CSS box model?

  1. Border: It represents the padding and content around the border.
  2. Content: It defines the actual content to be displayed.
  3. Margin: It represents the top layer of the box element
  4. Padding: It defines the empty space around the element

48. What is DOM?

The Document Object Model (DOM) can be defined as a cross-platform programming interface that defines HTML and XML documents as objects and nodes. It will define the logical structure of the documents and document manipulated. DOM allows the programmers to create, modify, delete the document structure, content, and style.

49. List the properties of transitions in CSS3?

  1. transition-delay
  2. transition-duration
  3. transition-property
  4. transition-timing-function

50. Define media queries in CSS3?

Media queries in CSS define styles in CSS that are responsive based on the different shapes and sizes of the viewing window.

They are used to adjust the entities given below:

  1. Height
  2. Width
  3. Viewport
  4. Resolution
  5. Orientation

Web Developer Interview Questions and Answers

51. What is Cross-Site Scripting (XSS)?

XSS means Cross site scripting can be defined as a common attack vector that will inject malicious code into the vulnerable web application. Stored XSS, also called persistent XSS, is the more damaging. It will occur when we inject a malicious script directly into a vulnerable web application.

52. Define float and z-index in CSS?

Float can be defined as a popular property in CSS that is used to control the position and layout of an element on a web page.

div  { float: right; }

In CSS, Z-index can be defined as a property that defines the order of elements on a web page. It majorly works on the basis of order indices; a higher-order element has to appear before a lower-order element.

53. Define HTML5 Web Storage?

With web storage, The web applications were able to store data locally within the user’s browser. Before HTML5, application data was stored in cookies that were included in each and every server request. Web storage is more secure, and huge amounts of data are stored locally without affecting the website’s performance.

54. Differentiate between ES5 and ES6?

It is a fifth edition of the ECMAScript.It is a sixth edition of the ECMAScript.
We can only define the variables only using the var keyword.We can define variables in two ways(let and const).

Apart from technical questions, you need to get prepared for some of the general and behavioral questions, and you may face these kinds of questions in your interview. I have listed a few; make sure you go through them as well.

55. Do you have any experience in developing multilingual websites?

56. How to handle a client who is unhappy with your team’s web delivery?

57. Have you gone through our company’s website? Can you mention what you didn’t like about the site?

58. Tell me about yourself?

59. Why should we hire you?

60. What are your strengths and weaknesses?

Good luck with your Web Developer Interview, and we hope our Web Developer Interview Questions and Answers were of some help to you. You can also check our CSS Interview Questions and Answers, PHP Interview Questions and Answers, and Java Interview Questions.

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