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Top 40 jQuery Interview Questions Answers for freshers and experienced

 jQuery Interview Questions Answers for freshers and experienced

Question-1 What is jQuery?

Answer: jQuery is not a programming language but a well written JavaScript code. It is a JavaScript code, which do document traversing, event handling, Ajax interactions and Animations.
Question-2 Why jQuery is needed?
Answer: jQuery is needed for the following list:
  • Used to develop browser compatible web applications
  • Improve the performance of an application
  • Very fast and extensible
  • UI related functions are written in minimal lines of codes

Question-3 What are the methods used to provide effects?

Answer: Some of the effects methods are:
  • Show()
  • Hide()
  • Toggle()
  • FadeIn() and
  • FadeOut()

Question-4 What are the four parameters used for jQuery Ajax method?

Answer: The four parameters are
  • URL – Need to specify the URL to send the request
  • type – Specifies type of request(Get or Post)
  • data – Specifies data to be sent to server
  • Cache – Whether the browser should cache the requested page

Question-5 What is CDN?

Answer: CDN is abbreviated as Content Distribution network and it is said to be a group of companies in different location with network containing copies of data files to maximize bandwidth in accessing the data.
Question-6 What are the two types of CDNs?
Answer: There are two types of CDNs:
Microsoft – Load jQuery from Ajax CDN
Google – Load jQuery from Google libraries API
Question-7 What are the types of selectors in jQuery?
Answer: There are three types of selectors in jQuery:
  • CSS Selector
  • XPath Selector
  • Custom Selector

Question-6 Is it possible that jQuery HTML work for both HTML and XML document?

Answer: No, jQuery HTML only works for HTML document. It doesn't work for XML documents.
Question-7 What is the use of html() method in JQuery?
Answer: The jQuery html() method is used to change the entire content of the selected elements. It replaces the selected element content with new contents.
Syntax:
Question-8 Is jQuery library used for server scripting or client scripting?
Answer:It is a library for client-side Scripting.
Question-9 What is the starting point of code execution in jQuery?
Answer:$(document).ready() function is the starting point of jQuery code. It is executed when DOM is loaded.
Question-10 Can you use any other name in place of $ (dollar sign) in jQuery?
Answer:Yes, instead of $ (dollar sign) we can use jQuery as a function name.
For example:
Question-11 What is the use of val() method in JQuery?
Answer:The jQuery val() method is used:
  • To get the current value of the first element in the set of matched elements.
  • To set the value of every matched element.

1-Getting the value of an input field:

2-Setting the value of an input field:

Question-12 What is the use of text() method in JQuery?

Answer:The text() method in jQuery is used to get the combined text contents of all matched elements, including their descendants, or set the text content of the matched elements. It is useful for manipulating or retrieving the text content within HTML elements.

Here are some common use cases for the text() method:
1-Getting the text content of an element:
2-Setting the text content of an element:
Question-13 Can you use multiple document.ready() function on the same page?
Answer:Yes. You can use any number of document.ready() function on the same page. For example:
Question-14 What is the difference between the ID selector and class selector in jQuery?
Answer: ID selector and class selector are the same as they are in CSS. ID selector uses ID while class selector uses a class to select elements.
You use an ID selector to select just one element. If you want to select a group of elements, having the same CSS class, use class selector.
Question-15 What is the difference between jQuery and JavaScript?
Answer:The difference between jQuery and JavaScript can simply be explained. 
JavaScript can simply be interpreted as a high-level application language whereas, jQuery can be interpreted as a library that is built within the JavaScript language & helps in the better functioning of JavaScript. 
Question-16 What is the use of delay() method in JQuery?
Answer:In jQuery, the delay() method is used to set a time delay before the execution of the next item in the queue. This can be useful when chaining multiple animations or effects together, and you want to introduce a pause between them.
Question-17 What is a use of jQuery filter?
Answer:In jQuery, the filter() method is used to narrow down the set of matched elements in a selection based on certain criteria. It allows you to filter a set of elements based on a specified condition and create a new jQuery object containing only the elements that meet that condition.
Question-18 What is the use of serialize() method in JQuery?
Answer:The jQuery serialize() method is used to create a text string in standard URL-encoded notation. It serializes the form values so that its serialized values can be used in the URL query string while making an AJAX request.
Question-19 Does Bootstrap require jQuery?
Answer:jQuery is used for JavaScript plugins by Bootstrap. However, if we use the CSS part of Bootstrap, jQuery is not needed.
Question-20 List some features of jQuery. 
  • DOM manipulation and traversal  
  • Event handling 
  • Effects and animations 
  • AJAX support 
  • Cross-browser compatibility 
  • Support for plugins and extensions 

Question-21 What is the use of the CSS () method in jQuery? 

Answer:The CSS () method in jQuery is used to retrieve or set the value of a CSS property for the selected elements.

Question-22 Which jquery method is used to hide selected elements? 
Answer:The hide() method in jQuery is used to hide selected elements.
Question-23 What is window.location.reload()?
Answer:window.location.reload() is a JavaScript method that belongs to the Location interface. It is used to reload the current URL, effectively refreshing the page. When you call window.location.reload(), the browser reloads the current document, fetching it from the server and replacing the existing content.
Question-24 Explain how CSS classes can be manipulated in HTML using jQuery.
Answer:jQuery allows for the manipulation of CSS classes in HTML through the use of the addClass(), removeClass(), and toggleClass() methods. The addClass() method is used to add a CSS class to an HTML element, while the removeClass() method is used to remove a CSS class from an HTML element. 
Question-25 State some different types of jQuery methods.
Answer:Some different types of jQuery methods include:
  • Event methods: such as click(), hover(), and focus()
  • Traversing methods: such as children(), parent(), and siblings()
  • DOM manipulation methods: such as append(), prepend(), and replaceWith()
  • CSS manipulation methods: such as addClass(), removeClass(), and CSS()
  • Animation methods: such as animate(), fadeIn(), and slideUp().

Question-26 Explain the operation of the jQuery connect() method.

Answer:The jQuery connect() method creates a connection to a remote server using the WebSockets protocol. It allows for real-time communication between the client and server, enabling the ability to push data from the server to the client in real-time.

Question-27 What is the exact difference between the methods onload() and document? ready()? 

Answer:The onload() method is JavaScript when the page finishes loading. The document. a Ready () method is a jQuery method called when the DOM is ready. The main difference is that onload() waits for all assets on the page to be loaded, including images and other external resources, during the document. Ready () only remains for the DOM to be prepared. 
Question-28 What are events in jQuery? 
Answer:Events in jQuery are actions or occurrences in the browser, such as a user clicking a button or hovering over an element.
Question-29 What is the significance of jQuery.length? 
Answer:jQuery.length is a property that returns the number of elements in the selected jQuery object. 
Question-30 What is jQuery click event? 
Answer:The click event in jQuery is triggered when a user clicks on an element. It can perform a specific action when an element is clicked. 
Question-31 Can you explain about ajaxStart() functions?
Answer:The ajaxStart() function in jQuery is a method triggered when an AJAX request is sent. It can perform a specific action when an AJAX request is sent, such as displaying a loading message.
Question-32 Can you explain the ajaxComplete() function?
Answer:The ajaxComplete() function in jQuery is a method that is triggered when an AJAX request is completed. It can perform a specific action when an AJAX request is completed, such as hiding a loading message.
Question-33 Can you say something about jQuery each() method?
Answer:Each () method in jQuery is used to iterate through a set of elements and perform a specific action on each element. It can loop through a set of elements and perform a specific action on each element.
Question-34 Distinguish between jquery.min.js and jquery.js.
Answer:jquery.min.js is a minified version of the jQuery library, which has been compressed to reduce its file size. 
Question-35 What exactly is a jQuery Data Table plugin? Also, explain the uses with examples.
Answer:A jQuery Data Table plugin is a tool that allows for easy manipulation and organization of data in a table format. This can include sorting, searching, pagination, and other features. For example, a website displaying a large amount of data in a table format could use a jQuery Data Table plugin to allow users to sort and search through the data easily. 
Question-36 Why are Ajax methods preferred in jQuery?
Answer:jQuery Ajax methods are simple, offer cross-browser support, send GET and POST requests and load XML, JSON, Scripts or HTML.
Question-37 How is parent() method in jQuery different from parents() method?
Answer:The parent() function travels only a single level in the DOM tree, whereas parents() searches through the entire DOM tree. 
Question-38 Explain the use of the event.preventDefault() method.
Answer:The event.preventDefault() method is used to prevent the default action of an event from occurring. 
Question-39  What are the benefits of Using jQquery instead of javascript in an ASP.NET web application?
Answer:Some benefits of using jQuery instead of JavaScript in an ASP.NET web application include built-in cross-browser compatibility support, a large library of pre-built functions, and a simpler and more consistent syntax.
Question-40 What is event.stopPropagation()?
Answer:The event.stopPropagation() method stops an event from propagating to parent elements.
 
 
 
 
 

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Brijesh Kumar

Database Developer

I have more then 6 years Experience in Microsoft Technologies - SQL Server Database, ETL Azure Cloud - Azure SQL Database, CosmosDB, Azure Data Factory, PowerBI, Web Job, Azure Function, Azure Storage, Web Apps, Powershall and Database Migration On-Premise to Azure Cloud.
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