Web Developer Interview Question and Answer

1. What is a pseudo-class?

Ans. It is a CSS technique that sets the style when an element changes its state. E.g. style changes when mouse hover, different styles for visited or unvisited links, etc.

There are four different types of pseudo-classes:

• Links: These pseudo-classes are used to style the link both in its normal state by default and when it has already been visited
• Dynamic: Dynamic pseudo-classes can be applied to any element to define how they are shown when the cursor is located on them, or by clicking on them or when they are selected
• Structural: Structural pseudo-classes allow to style elements based on an exact numerical position of the element
• Others: Some elements can be styled differently based on the language or what type of label they are not.

2. What is Name spacing in JavaScript?

Ans. It is usually not a good practice to use global variables in programming languages including JavaScript. However, you may have to use global variables sometimes. So, JavaScript introduces the concept of names pacing which ties down a part of the code and registers it with a uniue name.

The namespace is nothing more than a container name where we hold classes, functions, and variables that can be repeated with the same name in other namespaces or namespace without involving an error.

3. How can you reduce page loading time?

Ans. These are the following ways you can reduce web page loading time –

• Reduce the image size
• Use the latest generation formats for images
• Minify HTML, CSS, and Javascript
• Postpone uploading off-screen images
• Create Accelerated Mobile Pages ( AMPs)
• Remove unnecessary widgets
• Avoid multiple redirects
• Place CSS at the top and script referencing at the bottom or external files
• Reduce lookups
• Minimize redirects and caching
• Check the current speed of the website
• Finding a good hosting to host your website
• Clean the web code

4. What is CORS? Why is it important?

Ans. Cross-Origin Resource Sharing (CORS) is a browser mechanism that allows controlled access to resources located outside of a given domain. It enables a web page from one domain to access a resource with a different domain (a cross-domain request). It is a relaxation of the same-origin policy implemented in modern browsers. 

Due to the same-origin policy followed by XMLHttpReuest and fetch, JavaScript can only make calls to URLs that live on the same origin as the location where the script is running. Without features like CORS, websites are restricted to accessing resources from the same origin through the same-origin policy.

5. What are the advantages of HTTP 2.0 over HTTP 1.1?

Ans. The major advantages of HTTP 2.0 over HTTP 1.1 include – 

• Higher loading speed
• Improvement of web positioning
• Automatic prioritization
• Less broadband consumption
• Immediate presentation

6. How do you take into account SEO, maintainability, UX, performance, and security when you’re building a web application?

Ans. Explain how you prioritize your actions as per the requirements of the organization. If your organization handles vital data, then security will be your top priority. If it is a medium-sized online business, SEO and UX might be your top priority, and so on.

7. What are the new form elements introduced in HTML5?

Ans. The new form elements introduced in HTML5 are:

• <datalist> – specifies a list of options for input controls
• <keygen> – generates an encryption key
• <output> – defines the result of an expression
• <progress> – heads only in the direction of 100% of the max value
• <meter> – provides for a gauge, displaying a general value within a range

8. What’s the best way to integrate 5 different stylesheets into a website?

Ans. It usually depends on how the site is laid out. However, the most efficient way would be using just one file called styles.css (or similar). If you want to change the style, you just open up styles.css, scroll to find the relevant section, and modify the CSS. You can link the sheet in your HTML as –

<link rel=”stylesheet” href=”styles.css”>

9. What’s the difference between Canvas and SVG?

Ans. Canvas is an HTML5 element that can draw graphics on the fly with the help of JavaScript. SVG (Scalable Vector Graphics) is used to display vector-based graphics on the web. The major differences are –

10. What is the default border size of a Canvas?

Ans. There is no default border size of a Canvas. You can adjust using CSS.

11. What is the difference between IDs and Classes?

Ans.

12. What is your preferred development environment?

Ans. This question is not about checking if you are perfect for the same environment as the organization works but to measure if you are flexible to work in any environment. So, give them a hint that you are able to adapt to any environment with the core skills that you have.

13. Which are the new APIs provided by HTML5?

Ans. The new APIs are –

• Media API
• Text track API
• Application cache API
• Data transfer API
• User interaction API
• Command API
• Constraint validation API
• History API

14. What are your key responsibilities in your current organization?

Ans. You can talk about your current job role in a reply to this question. Usually, the most common job responsibilities of a web developer include –

• Writing well designed, testable, efficient code by using best software development practices
• Creating website layout/user interface by using standard HTML/CSS practices
• Integrating data from various back-end services and databases
• Gathering and refine specifications and requirements based on client’s requirements
• Creating and maintain software documentation
• Maintaining, expand, and scale the websites
• Staying plugged into emerging technologies/industry trends, and apply them to operations and activities
• Meeting with clients or management to discuss the needs and design of a website
• Cooperating with web designers to match visual design intent
• Creating and test applications for a website
• Writing code for the website, using programming languages such as HTML or XML
• Integrating graphics, audio, and video into the website

15. What is the difference between null value and undefined value?

Ans. Undefined means a variable has been declared but has not yet been assigned a value. On the other hand, null is an assignment value.

16. What are the web technologies that you are proficient in?

Ans. As already mentioned, you must have expert skills in three technologies: HTML5, CSS3, and JavaScript. Apart from that, you should be able to have at least some working knowledge of some of the other technologies like popular frameworks, APIs, and database management.

17. What are the different types of pop-up boxes available in JavaScript? Explain them.

Ans. There are three types of pop-up boxes:

• Alert – it just displays a message with an OK button.
• Confirm – it pops up a confirmation message window with the OK and Cancel button.
• Prompt – it pops up a dialog box asking the user input followed confirmation buttons.

18. What is Scope in JavaScript? Name the different types of Scopes.

Ans. The scope defines the accessibility of the functions and variables in an application. There are two types of scopes: local and global.

19. What is the difference between ‘==’ and ‘===’ operators?

Ans. Though both of them belong to the comparison operator category, the ‘==’ operator checks the value whereas, the ‘===’ operator checks both the value and the type.

20. By which mechanism in JavaScript can you detect the operating system on a client machine?

Ans. The operating system on a client system can be known by using the JavaScript property navigator.appVersion.

21. Which one do you use the most, CSS Animations or JavaScript Animations?

Ans. Both. CSS animation and JavaScript animation are the two primary ways of creating web animations. As per the project requirement and the kind of the desired effect, I have used both of them.

Cases when CSS animations work well:

• When the transitions are simple. For example, toggling within the element states.
• When the UI elements are self-contained. Like in showing a tooltip.

Cases when JavaScript animations work well:

• When advanced animation effects are expected in the project, like bouncing, stop pause, etc.
• When a superior level of control is required, JS animation works well.
• Helpful when drawing in HTML canvas.

22. Have you used Git for pushing live changes on the website?

Ans. Yes, Git is a great help to streamline live updates on the website. For this, I made use of a post-receive hook. Through this, I was able to copy updates from the remote server repo and update them onto the live site.

23. Which web development tools do you use?

Ans. There are several web development tools available and being into the role of a web developer, I have used multiple of them like:

• GitHub to work together with a team on a particular project.
• CodeKit to minify, combine, and syntax-check in JavaScript.
• JS to structure the web application and even develop a one-page application.
• CodePen to deploy a website and build test cases.
• Grunt for automating repetitive tasks.

24. As a web developer, how do you optimize your site’s loading time?

Ans. As a developer, I will optimize the site by –

• Implementing caching
• Minifying CSS, HTML, and JavaScript codes

25. How is HTML different from XHTML?

Ans. HTML and XHTML are both known for writing web pages. But, HTML is extended from SGML tagging whereas XHTML is an application of Extensible Markup Language (XML).

HTML has three components – element tag pair (start tag and end tag), attributes of the element within the tag, and content in the form of both text and graphics. Whereas XHTML includes only a single root element which includes lower case elements and the value that is assigned should be closed, nested, and must be surrounded by quotation marks. Looking at the difference, XHTML is more expressive when compared to HTML.

26. Have you gone through our website? Please mention what you didn’t like about the site?

Ans. Now, this is a tricky question and here the interviewer is checking your skills to identify what is good as per you and as a developer how in-depth knowledge do you have about the site’s functionality. So, the first thing is that you must visit their website before appearing for the interview as this will show your interviewer that you are serious about the role and at the same time you are well-prepared.

Next, you need to do is observe some good points about the site from a developer’s point of view and also make a checklist of pitfalls. Note, please mention only genuine points where your expertise can be of help.

27. How do you handle a client who is unhappy with your team’s web delivery?

Ans. For every company, the client is the king and no one wants to lose his or her clients at any cost. Therefore, when appearing for a web developer interview round, you must be well prepared as the recruiter can shoot this question.

You can start by narrating any previous incident that is related to client handling. Define the issues the client was facing, and later narrate the solutions, which you or your team had performed to help the client. This will let the recruiter know that you have the capability to handle and nurture clients.

28. What do you know about HTTP/3?

Ans. HTTP/3 is the new third-generation HTTP standard that was recently made available in late 2019. It is known for its new standards, fast, reliable, and secure connection. HTTP/3 promises a faster web experience as it uses UIC. This new internet transport protocol introduces first-class citizens. Brands like Google and Facebook are now using UIC because of its swift ability to speed up the web.

29. What will you do when an image or a hyperlink is not displaying correctly?

Ans. Many times it happens that some images are not properly displayed on the page and that severely affects the SEO and if happens multiple times, it hampers the overall rankings. So, I keep on checking things like missing href and alt tags.

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

Ans. It is not necessary that you hold experience in developing multilingual sites but you must know the basics of how it is done. You can tell the recruiter the process that involves Unicode encoding and usage of the ‘lang’ attribute.

31: What are the different HTTP request types supported in Restful Web Services? Can you explain the purpose of each?

Ans. Restful web services supported HTTP request types are GET, POST, PUT, and DELETE.

The purpose of each of the HTTP request types in Restful web service is:

1. GET

Also known as the idempotent method, GET retrieves data from the server. 

2. POST

POST is used for creating a new entity i.e. a resource without an ID.  On the creation of a request, the ID of the newly created entity is returned as part of the response to this HTTP request. It is often used while uploading a file or submitting a completed web form.

3. PUT

To update an existing entity. 

4. DELETE

To remove the resource from the server. 

32. What is Type Coercion in JavaScript?

Ans. Type coercion refers to the conversion of a value from one type to another (e.g Number to String, String to Number, or Boolean to Number) with similar content. In case the behavior of the implicit conversion is not sure, then the constructors of a data type can be used to convert any value to that datatype.

33. What is an ETag and how does it work?

Ans. An entity tag or an ETag is an HTTP header that is used for web cache validation and conditional requests from browsers for resources. It is allocated by a web server to a specific version of a resource found at a URL.  When the server reads the ETag from the client request, the server can then tell whether to send the file or tell the client just to use their local copy.

34. What is npm? [Node.js]

Ans. npm stands for Node Package Manager. It is a package manager for JavaScript. npm puts modules in place so that nodes can find them. npm also manages dependency conflicts. It is used to publish, discover, install, and develop node programs.

35. What is Webpack? 

Ans. Webpack is a static module bundler for JavaScript. It is a build tool that is used is to bundle JavaScript files for usage in a browser. It puts the bundles of assets, such as codes, images, fonts, and files in a dependency graph, and enables you to use require() in your source code to point to local files, like images, and decide how they’re processed in the final Javascript bundle.

While a webpack may slow you down at the beginning, it can give you great speed benefits when used correctly.

36. What is DOM (Document Object Model)? [CSS]

Ans. The Document Object Model (DOM) is a cross-platform programming interface that represents HTML and XML documents as nodes and objects. In simple terms, it defines the logical structure of documents and the way the documents are accessed and manipulated. DOM enables programmers to create, modify, and delete the document structure, style, and content. 

When a document is displayed on a browser, the content of the document must be combined with its style information. The browser converts HTML and CSS into the DOM. The DOM combines the document’s content with its style.

37. What is Cross-site Scripting (XSS)?

Ans. Cross-site scripting (XSS) is a security exploit that enables an attacker to introduce malicious client-side code into a website. When the untrusted links are unintentionally clicked by the victims, the cookies information is passed to the attackers so that they can bypass access controls.

38. What is the difference between responsive design and adaptive design? 

Ans. The responsive design follows the principle of flexibility. It adapts to the size of the screen and offers the optimal viewing experience of a website regardless of what type of device is used to see it. Responsive websites use CSS media queries and flexible grids to change styles based on different factors related to the device, such as display type, width, and height.  

Adaptive design uses static designs instead of flexible layouts. Its design is based on breakpoints that do not respond once they are initially loaded. It detects the type of device used and its other features, then provides the feature and layout based on a predefined set of characteristics. 

Similarity: Both responsive and adaptive designs optimize the user experience across different target devices. Both adjust for different viewport sizes, resolutions, and control mechanisms.

39: What is progressive rendering in HTML?

Ans. Progressive rendering or Progressive Server Side Rendering is a technique with which you can sequentially update small parts of the entire webpage and stream it to the client in parts without waiting for the whole page to be rendered. 

It means that when you start rendering the critical content on the server, you can stream it to the client without waiting for non-critical content to be rendered. It bridges the benefits of both CSR (Client Side Rendering) and SSR (Server Side Rendering). 

40. Explain the functional and non-functional requirements?

Ans. Functional requirements define the specific functionality of the system, It describes what the system does or must not do. 

Non-functional requirements, on the other hand, define how the system should do it. It specifies a system’s type, in terms of accessibility, reliability, capacity, usability, maintainability, and security. Non-functional requirements describe system behavior, features, and general characteristics that affect the user experience.

Non-functional requirements do not affect the basic functionality of the system. The system will continue to perform its basic purpose, even if the non-functional requirements are not met.

41. What is the difference between span and div tag in HTML5?

Ans. The following are the differences between <Div> tag and <Span> tag. 

42. What are CSS selectors? Name some.

Ans. CSS selectors are a part of a CSS ruleset. With CSS selectors, you can “find” HTML elements you want to style. They select HTML elements according to their id, class, type, attribute, etc.

There are several different types of selectors in CSS.

• Element Selector
• Id Selector
• Class Selector
• Universal Selector
• Attribute selectors
• Pseudo-Classes 
• Pseudo-Elements
• Combinator

43. Explain quirks, full standards, and almost standards mode.

Ans. quirks, full standards, and almost standards mode are the three modes for layout engines in web browsers. 

In quirks mode, the layout emulates nonstandard behavior in Navigator 4, Internet Explorer 5. This is typically used for the websites that were built before the introduction of web standards. 

In full standards mode, the behavior is described by the HTML and CSS specifications. Most modern browsers use this mode.  

In almost standards mode, there is only a small number of quirks implementation.

44. What is HTML5 Web Storage?

Ans. HTML5 web storage enables your web applications to store data locally within the user’s browser. The data is stored in name/value pairs, and a web page can only access data stored by itself.

In simple terms, web storage allows large amounts of application data to be stored locally. It does not affect the performance of your web application.

There are two types of web storage to store data locally:

• Local storage: This stores data with no expiration date. The data once stored in the local storage will be present even when the user’s browser is closed and reopened.
• Session storage: It stores data for one session only. The data will be deleted from the browser once the user’s browser is closed and the session would be lost. 

45. What is the difference between ES5 and ES6?

Ans. ES5 is an abbreviation of ECMAScript 5 while ES6 is an abbreviation of ECMAScript 6. ECMA is a trademarked scripting language specification defined by ECMA International. The difference between ES5 and ES6 are: 

46. What is long polling?

Ans. Long polling is a technique of having a persistent connection with the server. In long polling, the client polls the server requesting new information. The server holds a client’s connection open for as long as possible. The connection is closed only after the data is sent back to the client or connection timeout occurs.

Long Polling Flow:

• A request is sent to the server.
• The server holds a client’s connection until new data is available.
• The server responds to the request when the new information appears.
• The browser immediately sends another request.

47. What is DTD (Document Type Declaration)? What are its advantages?

Ans. DTD (Document Type Declaration) defines the structure of an XML document, i.e. what elements and attributes are permitted. It can be declared inside an XML document (inline) or as an external reference. 

• Internal DTD Declaration: When a DTD is declared within the file
• External DTD Declaration: When a DTD is declared in a separate file.

The advantages of DTD are:

1. It provides validating parsers with a map of how to validate the XML document.
2. It enables you to define your own format for the XML files enabling users and developers to understand the structure of the data.

48. Explain what is the difference between local storage and cookies?

Ans. The differences between local storage and cookies are:

49. What are CSS transitions? What are their properties?

Transitions in CSS3 enable the element to smoothly and gradually change from one state to another. They are easy to use and provide efficient animation effects. Two main properties that are required in transition:

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

50. How to handle type conversion in JavaScript?

Ans. JavaScript is a weakly typed language. It means that whenever an operator or statement expects a particular data-type, JavaScript automatically converts the data to that type. Javascript supports automatic type conversion. It is the common way of conversion of types used by JavaScript developers.

51. Explain the use of media queries in CSS3?

Ans. Media queries are used to define styles in CSS. They enable you to format the documents so that they can be presented correctly on different sizes of output devices like desktops, smartphones, and tablets.

Media queries are used for the following:

• Orientation: Landscape or Portrait
• Hide Elements
• Change Font Size
• Adjust Height and Width 
• Adjust Resolution

52. What is the use of float property in CSS?

Ans. Float is a popular property in CSS to control the layout and position of an element on a web page.

CSS Syntax

float: none|left|right|initial|inherit;

Float Property Values

53. Explain the difference between <window.onload> and <onDocumentReady>?

Ans. Both <window.onload> and <onDocumentReady> functions are used to perform tasks when the page is loaded in the browser. The following are the differences between them:

54. What is the use of .each() function in jQuery?

Ans. The .each() method is used to iterate over a set of elements in jQuery. It specifies a function to run for each matched element and allows us to loop through different datasets such as arrays or objects. To return the loop early, we can return false from the callback function.

Syntax:

$(selector).each(function(index,element))

The .each() accepts a parameter function(index,element), which is the callback function that executes for each selected element. This function reuires two parameters (optional), namely, index and element. A callback function needs to be passed to the .each() method.

55. What is the content delivery network (CDN) in jQuery? What are its benefits?

Ans. A Content Delivery Network (CDN) is an interconnected system of computers that exist all over the world and cache files for users to access. It provides web content quickly to users by duplicating or caching the content on multiple servers and directing the content to users in proximity. A CDN offers many advantages. Some of them are: 

1. Faster content delivery.
2. Significantly reduces the load time of a page. 
3. Lower network latency and packet loss.
4. Provides higher savings in the bandwidth.
5. Reduces bandwidth consumption.
6. Segmenting the audience becomes easy.
7. Offer better usage analytics.
8. Offer secure storage capacity for content.

56. What are the different types of CDNs supported in jQuery?

Ans. The two most popular CDNs supported in jQuery are:

1. Google: 

It is used to jQuery from the Google libraries API

Code to load jQuery Framework from Google CDN

Copy Code<script type=”text/javascript” src=”http://ajax.googleapis.com/ajax/libs/juery/1.9.1/juery.min.js”> 

</script>

2. Microsoft:

It is used to load from jQuery AJAX CDN

Code to load jQuery Framework from Microsoft CDN

Copy Code<script type=”text/javascript”

    src=”http://ajax.microsoft.com/ajax/jQuery/jQuery-1.9.1.min.js”>

</script>

57. What is the use of comments in JavaScript?

Ans. JavaScript comments are used to explain the source code and to make it more readable for the end-user. They also prevent some code lines from being executed during testing.

There are two types of comments in JavaScript: 

1. Single-line comments: 

It is used to comment a part of a line or a full line of code in JavaScript. “//” is used for single-line comment insertion

Example:

// Example of a single-line comment

2. Multi-line comments:

It is used to leave a long comment or commenting out a block of code. “/* */” is used to add multi-line comments.

Example:

/* Example

of a

multi-line

comment*/

58. What is ‘use strict’? What are its advantages?

Ans. ‘use strict’ is used to enable strict mode to automate stricter parsing and error handling when JavaScript code is run. This allows us to run a restricted variant of JavaScript. It enables us to assess the JavaScript code and throw more errors fix issues that may arise for future JavaScript releases.

The advantages of ‘use strict’ are: 

1. Eliminates some unreasonable features of Javascript syntax 
2. Eliminates some insecurities in the operation of the code 
3. Ensures the security of the code running
4. Improves compiler efficiency 

59. List the methods to provide effects in jQuery.

Ans. The following are some of the methods used to provide effects in juery:

• queue() – shows the queued functions on the selected elements
• show() – displays the selected elements
• hide() – hides the matched or selected elements
• delay() – sets a delay for all queued functions on the selected elements
• animate() – runs a custom animation on the selected elements
• fadeIn() – fades in the selected elements
• fadeOut() – fades out the selected elements
• toggle() – toggles between the hide() and shows() methods
• stop() – stops the currently running animation for the selected elements

60. What is z-index in CSS? 

Ans. The z-index property helps to specify the stack order of positioned elements that may overlap one another. The default value of z-index is zero and can take on either a positive or negative number. Overlapping elements with a higher z-index cover those with a lower index.

z-index property can have the following values:

• auto – Default value.
• initial – sets the property to its default value (0).
• number – Integer value. It can be positive or negative.
• inherit – Value inherited from the parent element.

61. What is W3C and why is it important? 

Ans. W3C stands for World Wide Consortium. It is an international community that focuses on developing, improving, and standardizing the web. W3C sets standards for the World Wide Web (WWW) and consists of several member organizations from a variety of IT-related industries. The mission of W3C is to lead the World Wide Web to its full potential and ensure its long-term growth. 

W3C is focused on developing protocols and guidelines for key aspects of the web, like HTML and CSS coding, XLM technology, web devices, and web browsing and authoring tools, etc. It helps developers to write one set of code and have it work everywhere. 

A web developer must enforce these standards to ensure that web content is accessible in all browsers to reach all audiences, as well as optimizes the user experience.  

62. What is Pagination in CSS?

Ans. Pagination refers to the process of dividing the document into pages and providing numbers to them. It is a sequence of pages on a website and is very important for content-heavy websites. Pagination reduces the scroll while reading as well as reduces the efforts to browse through specific pages which helps in increasing the value of the website. There are different types of Pagination in CSS, some of them are: 

1. Simple Pagination
2. Bordered Pagination
3. Centered Pagination
4. Rounded Border Pagination
5. Active and Hoverable Pagination
6. Rounded Active and Hoverable Buttons

We can implement Simple Pagination using the below syntax:

.pagination {

    display:type

}

.pagination body {

    color:colorname

    decoration:type

}

63. Explain the components of the CSS box model. 

Ans. The CSS box model is essentially an entity or a box that encloses all of the HTML elements. A box helps in creating layouts with CSS and in aligning items with other items. 

The box model allows us to add a border around elements, and to define space between elements.

A CSS box model has four components:

• Content – It is the actual content to be displayed.
• Padding – It refers to the empty space around the content. 
• Border – It is the border around the padding and content.
• Margin – It is the top layer of the box element. It refers to the empty space outside the border. 

64. Which CSS property will you use to add rounded corners to elements?

Ans. With the CSS <border-radius property>, we can give rounded corners to any element. This property defines the radius of an element’s corners and can be applied to any or all four sides as per the requirement. The CSS rounded borders will be noticeable if the colors of the background or borders differ from the colors that surround the rounded element.

The <border-radius> property has four attributes for setting CSS rounded borders to different edges:

• <border-top-left-radius>
• <border-top-right-radius>
• <border-bottom-left-radius>
• <border-bottom-right-radius>

65. How to diagnose and fix the browser freeze issue in Chrome, Firefox, and Edge?

Ans. The root cause of the browser freeze issue can be diagnosed and resolved using the below steps: 

• Identify and remove malfunctioning extensions

A malfunctioning add-on or extension can cause your browser to freeze. You can check the add-ons that you have installed and remove which you no longer need. Having too many extensions can also freeze or slow down your browser. 

• Reduce your browser’s memory usage

Browsers consume a lot of memory, especially if you have a lot of tabs open. If your computer doesn’t have that much RAM your browser might slow down or even crash.

• Disable unnecessary scripts

The unnecessary scripts running in the browser can cause it to freeze, including hangs and freezes. You can take the help of add-ons like NoScript for Firefox and uMatrix for Chrome that block plugins such as JavaScript, Java, Flash, etc. from running on sites other than those you have allowed. 

• Scan for malware

A malicious can mess with your browser’s security and cause connection problems. You must scan your browser for malware with any basic or built-in malware scanner.

• Reset and reinstall your browser

If you’ve tried everything and still the issue persists, then uninstall the browser and install the latest version.

66. What is pair programming?

Ans. Also known as pairing and programming in pairs, pair programming is a practice where two developers work using only one machine to solve the problems at hand. Each programmer will have a keyboard and a mouse. While one programmer (the driver) will perform the coding, the other (the observer) will check the code while also figuring out where to go next. The two programmers switch roles frequently. Below are some advantages of pair programming: 

• More efficient
• Two heads are better than one
• Fewer coding mistakes
• Great way to share knowledge
• Problems can be solves faster and quicker
• Enhancement of interpersonal skills 

This is an important web developer interview question, which is asked to check if you can work with other people easily and effectively.

67. What is Ajax?

Ans. AJAX stands for Asynchronous JavaScript and XML. It enables applications to transport data to or from a server asynchronously without refreshing the page. It means that parts of a web page are updated, without reloading the entire page. AJAX can be used anywhere in a web application where small amounts of information could be saved or retrieved from the server without posting back the entire page. This technique helps in creating better, faster, and interactive web applications. Below are some benefits of AJAX: 

• Helps in performing perform a callbacks
• Allows us to make asynchronous calls to a web server
• Improved the speed and usability of a web application
• User-friendly

68. What is Event Bubbling?

Ans. Event Bubbling is a type of event propagation in which one element is nested inside a second element, and both elements have registered a handle to that event. This process starts with the element that triggers the event and then bubbles up to the containing elements in the hierarchy. The event is first captured and handled by the innermost element and then successfully propagated to outer elements. Thus, when an event happens on an element, it first runs the handlers on it, then on its parent, then all other ancestors.