jQuery Interview Questions

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If you're looking for jQuery Interview Questions & Answers for Experienced or Freshers, you are at right place. There are lot of opportunities from many reputed companies in the world. According to research jQuery has a market share of about 45%. So, You still have opportunity to move ahead in your career in jQuery Development. Mindmajix offers Advanced jQuery Interview Questions 2019 that helps you in cracking your interview & acquire dream career as jQuery Developer.

Q. What is jQuery?

jQuery can simply be interpreted as most advanced JavaScript framework which is used for performing high-level applications which include feature-rich, fast,and  lightweight framework which assists in to through the HTML DOM, add Ajax interaction,build animations, manipulation of the page content, modify the alignment and render cool UI effect. This is a client-side scripting language.

Q. Can differentiate between jQuery and JavaScript?
The difference between the jQuery and the JavaScript can simply be explained. 
JavaScript can simply be interpreted as a high-level application language whereas, jQuery can be interpreted as a library which is built within the JavaScript language & helps in the better functioning of JavaScript. 

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

Q. Explain the basic requirement, to begin with, jQuery?
In order to get begin with the jQuery, all that one needs to do at the beginning is to make a reference to its complete library. After this, you will be having access to all the application files which are present within the library. jQuery latest version can now get downloaded from jQuery.com.

Q. Why exactly is the need for the use of jQuery?
jQuery is a highly programmed internal library for the better functioning of JavaScript. It handles a number of applications and its prominence can never be ignored. The following list will be depicting the reasons for why is the need to use jQuery?
* jQuery comes very handily for the purpose of designing user-friendly web applications.
* By making an effective use of jQuery the performance of an application can be greatly enhanced.
* Very fast and extensible.
* Only minimal lines of codes will be sufficient for writing UI related functions. 

Q. State different jQuery methods that are used to provide effects?
 jQuery has a set of methods implying which we can expect to provide different effects within the system. Some of the jQuery methods include  
* FadeOut()
* Toggle()
* Hide()
* Show()
* FadeIn() and

Q. Describe the minimized version of the jQuery and its benefits.
With the minimized version of the jQuery, the efficiency of the webpage can be greatly improved. The effectiveness of the webpage which is having a minimized version of jQuery will be a lot better than the effectiveness of the webpage which is having a normal js file.

This is the reason why most of the web pages are nowadays are found to have a minimized version of the jQuery. 

Q. Explain about different scenarios where jQuery can be effectively implemented?
jQuery is a highly advanced library application which extensively is used in following scenarios:
* Apply CSS static or dynamic functions.
* Calling functions on events.
* For the purpose of manipulation.
* For creating different animation effects.

Having the presence of all the advanced library applications jQuery is best at maintaining different applications with a higher degree of effectiveness. 

Q. Explain about the jQuery connect?
 jQuery connect can simply be interpreted as a plug-in which is used to connect or bind one function to the another. This will be helpful for executing the fro any other function or the plug-in is executed. 

Q. Which parameters are being used for the jQuery Ajax method?
JQuery Ajax method makes use of four different parameters which include
* URL – The URL must be clearly specified in order to send the request. 
* type – Specifies the type of request(Get or Post)
* data – Specifies data to be sent to the server
* Cache – This tells if the browser should index the specific page or not. 

Checkout jQuery Tutorials

Q. Explain the ways through which we can include jQuery on a page?
Including jQuery in a page can be done with the help of the following ways. 
* Local copy inside script tag
* Remote copy of jQuery.com
* By keeping a remote copy of Ajax API
* Making a local copy of script manager control
* Embedded script using client script object

Q. Differentiate the concepts of ID selector and class selector in jQuery?
Just like they are used in the CSS, both ID selector and Class selector are used for the same functioning .

In order explain the functioning of both the concepts in simpler words, ID selector uses ID while class selector makes use of a class to select the different elements.

In the case where you are needed to select only one element then we have to go with the ID selector. And if you want to select a group of elements, then we have to go with the class selector.

jQuery Practical Interview Questions & Answers

Q. Explain the exact purpose of the animate function in jQuery.
The animate function is extensively being used in the jQuery. It is an advanced concept which is well received by the audience. Well, the main feature of the animation function in jQuery is to apply the custom animation effect to different elements. 

The syntax for this function is as follows
Syntax:

$(selector).animate({params}, [duration], [easing], [callback])  

Here,
* "param" defines the CSS properties where are intended to apply the animation.
* "duration" it simply depicts for what exact period of time the animation will run. Its values are:   "slow", "fast", "normal" or it can even be milliseconds.
* "easing" is the string which specifies the function for the transition.
* "callback" it is the function with the help of which we can call an action upon the completion of the animation. 

Q. What is JQuery.noConflict?
In order to help the system to overcome the conflicts between the different libraries and frameworks the jQuery no-conflict option given by the jQuery. This concept is really advanced which has been developed over the recent times. In the case of any conflicts which arise between the libraries and frameworks using this jQuery.noConflict function will help in overcoming all the conflicts. 

Q. Explain the concept of fade effect in jQuery?
1. In jQuery there are three different applications applying which we can avail the fade effect. 

 Fade effect can be availed by using the functions which are fadeIn, fadeOut and fadeTo.

2. The opacity of elements gets changed with animation through the effect of these methods. 
The syntax for the fading effect includes 
Syntax:

$(selector).fadeIn(speed,callback)
$(selector).fadeOut(speed,callback)
$(selector).fadeTo(speed,opacity,callback)

 “speed” this can be one among the following values: “slow”, “fast”, “normal” or milliseconds.
“opacity” this is used to specify the capacity of fading to give opacity.
“callback” it is the function with the help of which we can call an action upon the completion of fading. 

Q. Explain the Struts2 jQuery plug-in and its advantages.
The struts2 jQuery plug-in is used to:
* Easy integration of Ajax and widgets will be provided to the user.
 * The extent of coding needed to be done will be reduced.

For ex:

Result Div

The advantages of using truts2 jQuery are:

1. It greatly reduces the extent of coding needed to be done for a particular action.
2. It also supports ajax form validation.
3. The readability levels of the code will be very high and so it will become much easier to perform the debugging. 

Q. Explain how the jQuery stores data related to an element?
Information of an element can be stored in the simple javascript by simply adding a domain object model property to the element. This results in the rising of issues such as leakage of memory in the browsers. 
But in the case of jQuery the user does not need to be bothered by the memory management issues.

For ex : Storing and retrieving data related to an element:

$(‘#myDiv’).data(‘keyName’, { foo : ‘bar’ });
$(‘#myDiv’).data(‘keyName’); // { foo : ‘bar’ }

Q. Describe the procedure of extracting a query string with regular expressions?
The procedure of extracting a query string with regular expressions can be done in two ways.
1. Approach of String-based: 
It is considered to be the simplest way in use for extracting a query string with regular expressions. This method is carried ahead by making the utilisation of the .replace() method to function.

For ex : 

var data = string.replace("http://localhost/view.php?", "");

The above procedure will be fine but it has some flexible issues. 

2. Regular expression approach:
This is the most powerful method for extracting a query string and the pattern must be used that seeks about the question mark among the string. When done, the JS regular expressions are delimited  

Q. Differentiate the concepts of .js and .min.js?
jQuery library has two different versions Development and Production. The other name for the deployment version is minified version. 

Considering the functionality, both the files they are much similar to each other. Being smaller in size, the  .min.js   gets loaded quickly saving the bandwidth.

Q. What is a CDN?

The term CDN relates to the concept of Content Delivery Network. In general, CDN can be interpreted as a large system of servers that are deployed in multiple data centers across the internet. 

CDN is mainly aimed at delivering the content to the end-users by enabling them to have high availability and high performance. 

Q. Explain the advantages of the CDN.

The benefits of CDN are quite effective in relation to the working functionality of the jQuery.
Some of the benefits of the CDN include

* CDN greatly diminishes the load from your server.
* Saving the bandwidth CDN helps the jQuery to load faster than the usual time
* The most prominent feature of the CDN is that it if any user visits a website which is running on jQuery it caches it.

Q. What is an event?PreventDefault?
The event.preventDefault() method function is to stop the default action of an element from taking place  or to halt the default action from happening. 

Q. Differentiate onload() and document.ready().
 
The main differentiating factor of onload() and document.ready() is that

At max, a page supports the existence of only one onload function, & all the other onload functions will be getting terminated

While coming to the document.ready function, a page can have more than one document.ready function. 
 
Also, the document.ready function is called when the DOM gets loaded and whereas the onload function gets called only when the DOM images get loaded on the page.
 
Q.  Why is jQuery better than JavaScript?
In general, jQuery is considered to be far better than the JavaScript. jQuery can be interpreted as an application for developing Ajax application and helps in simplifying the code & the code readability will also be good. 

jQuery also supports the creation of animations and delivers such high-level functionalities. 

Related Page: AngularJS Vs. JQuery

Q. Explain the types of selectors in jQuery?
There are three types of selectors in jQuery:
* CSS Selector
* XPath Selector
* Custom Selector

Q. Explain the concept of Grouping?

The concept of grouping can simply be explained as whenever the same declaration gets shared by more than one selector they get separated by a common separated list. 

This helps in greatly reducing the size of the CSS and helps it in making it become more readable. 

Q. Explain the concept of finish method in jQuery?

In order to stop all the queued animations and to help them place in their final state the .finish() method is used. This method was introduced in jQuery 1.9.

Q. Differentiate between calling stop (true, true) and finish method?

The .finish() method will be quite similar to .stop(true, true). It helps in clearing the queue & thereby helps the animations to enter into their end state. In .finish() it also causes the CSS property of all queued animations to jump to their end values, as well.

Q. Which is the latest version of the jQuery library?

The latest version (when this post is written) of jQuery is 1.10.2 or 2.0.3. jQuery 2.x has the same API as jQuery 1.x but does not support Internet Explorer 6, 7, or 8.

Q. Explain the concept of writing the browser specific code using jQuery?

We can write browser specific code by simply making use of the jQuery.browser property. This property contains flags for the user agent, read from navigator.userAgent. 

This property was excluded from jQuery 1.9.

Q. What is the procedure to check the data type of any variable in jQuery?

 By using $.type(Object) which returns the built-in JavaScript type for the object.