Top JQuery Interview Questions and Answers

 

Top JQuery Interview Questions and Answers :-

Here is the list of latest and updated Top JQuery Interview questions and answers for freshers as well as experienced users. so please take a look below :-

Q1. What is jQuery?

Ans: jQuery is fast, lightweight and feature-rich client side JavaScript Library/Framework which helps in to traverse HTML DOM, make animations, add Ajax interaction, manipulate the page content, change the style and provide cool UI effect. It is one of the most popular client side library and as per a survey it runs on every second website.

Q2. What are the core features of jQuery?

Ans: Following is the list of important core features supported by jQuery −

  • DOM manipulation − The jQuery made it easy to select DOM elements, traverse them and modifying their content by using cross-browser open source selector engine called Sizzle.
  • Event handling − The jQuery offers an elegant way to capture a wide variety of events, such as a user clicking on a link, without the need to clutter the HTML code itself with event handlers.
  • AJAX Support − The jQuery helps you a lot to develop a responsive and feature-rich site using AJAX technology.
  • Animations − The jQuery comes with plenty of built-in animation effects which you can use in your websites.
  • Lightweight − The jQuery is very lightweight library – about 19KB in size ( Minified and gzipped ).
  • Cross Browser Support − The jQuery has cross-browser support, and works well in IE 6.0+, FF 2.0+, Safari 3.0+, Chrome and Opera 9.0+.
  • Latest Technology − The jQuery supports CSS3 selectors and basic XPath syntax.

Q3. Whether jQuery HTML work for both HTML and XML documents?

Ans: No, jQuery HTML only works for HTML documents not for XML Documents.

Q4. What are the methods used to provide effects?

Ans: Some of the effects methods are:

  • Show()
  • Hide()
  • Toggle()
  • FadeIn() and
  • FadeOut()

Q5. How JavaScript and jQuery are different?

Ans: JavaScript is a language While jQuery is a library built in the JavaScript language that helps to use the JavaScript language.

Q6. Is jQuery replacement of Java Script?

Ans: No. jQuery is not a replacement of JavaScript. jQuery is a different library which is written on top of JavaScript. jQuery is a lightweight JavaScript library that emphasizes interaction between JavaScript and HTML.

Q7. Can a jQuery library be used for server scripting?

Ans: jQuery can be interpreted as an internally built library which is being used in the JavaScript. And jQuery is strictly been designed with the functionality of client-side scripting. jQuery is not compatible with server-side scripting.

Q8. What are the basic selectors in jQuery?

Ans: Following are the basic selectors in jQuery:

  • Element ID
  • CSS Name
  • Tag Name
  • DOM hierarchy

Q9. How can we debug jQuery?

Ans: There are two ways to debug jQuery:

Debugger keyword

  • Add the debugger to the line from where we have to start debugging and then run Visual Studio in Debug mode with F5 function key.
  • Insert a break point after attaching the process

Q10. What is the use of jQuery.ajax method ()?

Ans: jQuery.ajax method is used for asynchronous HTTP requests.

Q11. Where can we download JQuery?

Ans: jQuery javascript can be downloaded from jQuery official website – www.jquery.com

Q12. Is jQuery is a replacement of JavaScript?

Ans: No, jQuery is not a replacement of JavaScript.

Q13. What is called chaining?

Ans: Chaining is used to connect multiple events and functions in a selector.

Q14. What are the advantages of jQuery?

Ans: Following are the advantages of jQuery:

  • Just a JavaScript enhancement
  • Coding is simple, clear, reusable
  • Removal of writing more complex conditions and loops

Q15. Whether C# code behind can be called from jQuery?

Ans: Yes, we can call C# code behind from jQuery.

Q16. What is the use of jQuery.data() method?

Ans: jQuery data method is used to associate data with DOM nodes and JavaScript objects. This method will make a code very concise and neat.

Q17. What is the difference between onload() and document.ready()?

Ans: In a page, we can have only one onload function but we can have more than one document.ready function. Document.ready function is called when DOM is loaded but onload function is called when DOM and images are loaded on the page.

Q18. What is the use of jQuery each function?

Ans: jQuery each function is used to loop through each and every element of the target jQuery object. It is also useful for multi element DOM, looping arrays and object properties.

Q19. How method can be called inside code behind using jQuery?

Ans: $.ajax can be called and by declaring WebMethod inside code behind using jQuery.

Q20. Which is the fastest selector in jQuery?

Ans: ID and Element are the fastest selectors in jQuery.

Q21. What is the slowest selector in jQuery?

Ans: Class selectors are the slowest selectors in jQuery.

Q22. Where jQuery code is getting executed?

Ans: jQuery code is getting executed on a client browser.

Q23. What is the method used to define the specific character in place of $ sign?

Ans: ‘NoConflict’ method is used to reference a jQuery and save it in a variable. That variable can be used instead of Sign.

Q24. Why jQuery is better than JavaScript?

Ans: jQuery is a library used for developing Ajax application and it helps to write the code clean and concise. It also handles events, animation and Ajax support applications.

Q25. What are the types of selectors in jQuery?

Ans: There are three types of selectors in jQuery:

  • CSS Selector
  • XPath Selector
  • Custom Selector

Q26. What is the difference between jQuery.get() and jQuery.ajax()?

Ans: jQuery.ajax() is the all-encompassing Ajax request method provided by jQuery. It allows for the creation of highly-customized Ajax requests, with options for how long to wait for a response, how to handle a failure, whether the request is blocking (synchronous) or non-blocking (asynchronous), what format to request for the response, and many more options.jQuery.get() is a shortcut method that uses jQuery.ajax() under the hood, to create an Ajax request that is typical for simple retrieval of information. Other pre-built Ajax requests are provided by jQuery, such as jQuery.post(), jQuery.getScript(), and jQuery.getJSON().

Q27. Explain the difference between the .detach() and .remove() methods in jQuery.

Ans: The .detach() and .remove() methods are the same, except that .detach() retains all jQuery data associated with the removed elements and .remove() does not. so .detach() is therefore useful when removed elements may need to be reinserted into the DOM at a later time.

Q28. What does dollar sign ($) means in jQuery?

Ans: Dollar Sign is nothing but it’s an alias for JQuery. Take a look at below jQuery code.

$(document).ready(function(){
});

Over here $ sign can be replaced with “jQuery” keyword.

jQuery(document).ready(function(){
});

Q29. Can we have multiple document.ready() function on the same page?

Ans: YES. We can have any number of document.ready() function on the same page.

Q30. What is a CDN?

Ans: A content delivery network or content distribution network (CDN) is a large distributed system of servers deployed in multiple data centers across the Internet. The goal of a CDN is to serve content to end-users with high availability and high performance.

Q31. Which are the popular jQuery CDN? and what is the advantage of using CDN?

Ans: There are 3 popular jQuery CDNs.

  1. 1. Google.
  2. 2. Microsoft
  3. 3. jQuery.

Advantage of using CDN.

  • It reduces the load from your server.
  • It saves bandwidth. jQuery framework will load faster from these CDN.
  • The most important benefit is it will be cached, if the user has visited any site which is using jQuery framework from any of these CDN

Q32. How to load jQuery from CDN?

Ans: Below is the code to load jQuery from all 3 CDNs.
Code to load jQuery Framework from Google CDN

<script type="text/javascript"
    src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">
</script>

Code to load jQuery Framework from Microsoft CDN

<script type="text/javascript"
    src="http://ajax.microsoft.com/ajax/jquery/jquery-1.9.1.min.js">
</script>

Code to load jQuery Framework from jQuery Site(EdgeCast CDN)

<script type="text/javascript"
    src="http://code.jquery.com/jquery-1.9.1.min.js">
</script>

Q33. How to load jQuery locally when CDN fails?

Ans: It is a good approach to always use CDN but sometimes what if the CDN is down (rare possibility though) but you never know in this world as anything can happen.

Below given jQuery code checks whether jQuery is loaded from Google CDN or not, if not then it references the jQuery.js file from your folder.

<script type="text/javascript">
if (typeof jQuery == 'undefined')
{
  document.write(unescape("%3Cscript src='Scripts/jquery.1.9.1.min.js' type='text/javascript'%3E%3C/script%3E"));
}
</script>

It first loads the jQuery from Google CDN and then check the jQuery object. If jQuery is not loaded successfully then it will references the jQuery.js file from hard drive location. In this example, the jQuery.js is loaded from Scripts folder.

Q34. What are the fastest selectors in jQuery?

Ans: ID and element selectors are the fastest selectors in jQuery.

Q35. What are the slow selectors in jQuery?

Ans: class selectors are the slow compare to ID and element.

So here we read about “Top JQuery Interview questions and answers”.

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