Jquery


Jquery is a fast and concise JavaScript Library created by John Resig in 2006 with a nice motto: Write less, do more. jQuery simplifies HTML document traversing, event handling, animating, and Ajax interactions for rapid web development. jQuery is a JavaScript toolkit designed to simplify various tasks by writing less code.

Here is the list of important core features supported by jQuery −

 v  DOM manipulation − The jQuery made it easy to select DOM elements, negotiate them and modifying their content by using cross-browser open source selector engine called Sizzle.

 v  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.

 v  AJAX Support − The jQuery helps you a lot to develop a responsive and featurerich site using AJAX technology.

 v  Animations − The jQuery comes with plenty of built-in animation effects which you can use in your websites.

 v  Lightweight − The jQuery is very lightweight library - about 19KB in size (Minified and gzipped).

 v  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+

 v  Latest Technology − The jQuery supports CSS3 selectors and basic XPath syntax.




Advantages of Using jQuery

If you're not familiar with jQuery, you might be wondering what makes jQuery so special. There are several advantages why one should opt for jQuery:

v  Save lots of time : You can save lots of time and efforts by using the jQuery inbuilt effects and selectors and concentrate on other development work.

v  Simplify common JavaScript tasks : jQuery considerably simplifies the common JavaScript tasks. Now you can easily create feature rich and interactive web pages with fewer lines of codes, a typical example is implementing Ajax to update the content of a page without refreshing it.

v  Easy to use : jQuery is very easy to use. Anybody with the basic working knowledge of HTML, CSS and JavaScript can start development with jQuery.

v  Compatible with browsers : jQuery is created with modern browsers in mind and it is compatible with all major modern browsers such as Chrome, Firefox, Safari, Internet Explorer, etc.

v  Absolutely Free : And the best part is, it is completely free to download and use.


jQuery Features

Following are the important features of jQuery.

v  HTML manipulation

v  DOM manipulation

v  DOM element selection

v  CSS manipulation

v  Effects and Animations

v  Utilities

v  AJAX

v  HTML event methods

v  JSON Parsing

v  Extensibility through plug-ins



Why jQuery is required

Sometimes, a question can arise that what is the need of jQuery or what difference it makes on bringing jQuery instead of AJAX/ JavaScript? If jQuery is the replacement of AJAX and JavaScript? For all these questions, you can state the following answers.

v  It is very fast and extensible.

v  It facilitates the users to write UI related function codes in minimum possible lines.

v  It improves the performance of an application.

v  Browser's compatible web applications can be developed.

v  It uses mostly new features of new browsers.

So, you can say that out of the lot of JavaScript frameworks, jQuery is the most popular and the most extendable. Many of the biggest companies on the web use jQuery.

Some of these companies are:

v  Microsoft

v  Google

v  IBM

v  Netflix

jQuery History

jQuery was first released in January 2006 by John Resig at BarCamp NYC. It is currently headed by Timmy Wilson and maintained by a team of developers.

Nowadays, jQuery is widely used technology. Most of the websites are using jQuery.

jQuery Release History

Let's see the release dates of jQuery versions.

Version No.

Release Date

1.0

26,August,2006

1.1

14,January,2007

1.2

10, September, 2007

1.3

14, January, 2009

1.4

14, January, 2010

1.5

31, January, 2011

1.6

3, May, 2011

1.7

3, November, 2011

1.8

9, August, 2012

1.9

15, January, 2013

1.10

24,May, 2013

1.11

24, January, 2014

2.0

18, April, 2013

2.1

24, January, 2014


Q-1). What is Jquery?
Ans: jquery is javascript library which required a jquery.js file. After that you can write the jquery as fallows. It uses "$" as the short hand to write jquery code.
Simple Syntax is
  $(document).ready(function () {

         //function body
     });



Q-2).When Jquery founded and by whom?
Ans: It was released in January 2006 at BarCamp NYC by John Resig(Jquery founder).

Q-3).What scripting language is jQuery written in?
Ans: JavaScript

Q-4).Write a basic code for add jquery library to pages?
 
Ans:
 
<html>

<head>
  <script type="text/javascript" src="jquery.js"></script>
  <script type="text/javascript">
      // You can write the code here
  </script>
</head>
<body>
    <a href="http://www.tutoriz.com/">Jquery Interview Questions and  Answers</a>
</body>
</html>
  Q-5).What is jQuery Selectors? Give some examples.
Ans: Selectors are used in jQuery to find out DOM elements. Selectors can find the elements via ID, CSS, Element name and hierarchical position of the element.
Selector       Example                 Selects
 *                 $("*")                    All elements
 #id              $("#lastname")      The element with id=lastname
 .class          $(".intro")              All elements with class="intro"
 element      $("p")                     All p elements
For more click here
 http://www.w3schools.com/jquery/jquery_r...ectors.asp

Q-6).What
 $("div.tutoriz") will select?
Ans: All the div element with tutoriz class.

Q-7).JQuery uses CSS selectors and XPath expressions to select elements true or false?
Ans:- True

Q-8).What are the fastest selectors in Jquery?
Ans: ID and element selectors are the fastest selectors

Q-9).What are the slower selecoters in Jquery?
Ans: Class selectors are slower

Q-10).Which one is faster Jquery ID selector or JavaScript getElementById()?
 (Jquery ID selector vs JavaScript getElementById())
Ans: JavaScript getElementById() is faster than Jquery Id ($("#elementID")) selector

Q-11).Where Jquery code execute? On client browser or server browser?
Ans: On client browser

Q-12).Write the code for selecting the
 1st div element, 4th div element
 last div, and for even and odd div elemets also.
 one by one?
 apply the red color on the above div.
Ans:
<div class="questions">

     <div class="box"> Question</div>
     <div class="box"> Question</div>
     <div class="box"> Question</div>
     <div class="box"> Question</div>
     <div class="box"> Question</div>
     <div class="box"> Question</div>
</div>
  Code for first div          : $("div.questions > div:first").css("color", "red");
 Code for 4th div          : $("div.questions > div:nth-child(4)").css("color", "red");
 Code for last div          :
 $("div.questions > div:last").css("color", "red");
 Code for even div        :
 $("div.questions > div:even").css("color", "red");
 Code for odd div         :
 $("div.questions > div:odd").css("color", "red");

Q-13).Write the code for select second last div element?
Ans: Code for second last div :
 $("div.questions > div::nth-last-child(2)").css("color","red");
 <!-- Introduced in CSS3 -->

Q-14).What are the advantages of using jQuery over JavaScript in ASP.NET web application
 
Ans:
 Below are the advatages of using jQery over JavaScript
 a>.Jquery is well written optimised javascript code so
 it will be faster in execution unless we write same standard optimised javascript code.
 b>.Jquery is concise java script code ,means minimal ammount of code
 is to be written for the same functionality than the javascript.
 c>.Javascript related Development is fast using Jquery because most of the
 functionality is already written in the library and we just need to use that.
 d>.Jquery has cross browser support ,so we save time for supporting all the browsers.
 

Q-15).What is Chaining in jQuery?
Ans: In jQuery, Chaining means to connect multiple functions, events on selectors. look at Sample Code 1 and 2.
Sample Code 1
$(document).ready(function(){
     $('#dvContent').addClass('dummy');
     $('#dvContent').css('color', 'red');
     $('#dvContent').fadeIn('slow');
 });​

Sample Code 2
$(document).ready(function(){

     $('#dvContent').addClass('dummy')
           .css('color', 'red')
           .fadeIn('slow');    
 });​

Both the sample codes above will perform the exact same thing but the only difference is that Sample code 2 is using Chaining. But Code 2 is faster and shorter then Code 1.
 The problem with the Sample Code 1 is that for every statement, jQuery has to search the entire DOM and find the element and after that executes the attached function on it. But when chaining is used, then jQuery has to find the element only once and it will execute all the attached functions one by one. This is the advantage of Chaining.

Q-16).Is jQuery a library for client scripting or server scripting?
Ans: Client Script

Q-17).What is jQuery & its significance? Why it is so popular?...

Q-18).What are features of JQuery
 
 or
 
 What can be done using JQuery?

 Ans: Features of Jquery
 1. One can easily provide effects and can do animations.
 2. Applying / Changing CSS.
 3. Cool plugins.
 4. Ajax support
 5. DOM selection events
 6. Event Handling

Q-19).How to check Jquery UI loaded or not?
Ans: // Checking if jQuery UI is loaded or not
        if ($.ui) {

             // jQuery UI is loaded
         } else {
             // jQuery UI is not loaded
         } 
 Q-20).How check currently loaded jQuery UI version on the page?
 Ans: // Returns jQuery UI version (ex: 1.8.2) or undefined
 $.ui.version

Q-21).Write the code for setting datetimepicker on textbox click.
 If below is our textbox
<input type="text" id="Text1" name=%26quot%3Bacc%26quot%3B value="Select Date"/>  then Jquery code will be
$("#abc").datepicker();

Q-22).If you have a table, how you will apply the two differt color on alternate rows using Jquery?
<table border="1">

   <tr><td>Vikas Ahlawat</td></tr>
   <tr><td>Edwin George</td></tr>
   <tr><td>Rohit Khurana</td></tr>
   <tr><td>Gyan Singh</td></tr>
</table>
  Ans :
<script>

     $(document).ready(function () {
         $("tr:even").css("background-color", "#f4f4f8");
         $("tr:odd").css("background-color", "#ffffff");
     });
 </script>



Q-23).Name the Jquery method which is used to hide selected elements?
Ans: .hide()

Q-24).Name the Jquery methods which are used for apply css class?
 Ans:
$("#Id1").addClass('YourClassName'); // for apply class

$("#Id1").removeClass('YourClassName'); // for remove class
 Q-25).What is the use of attr() method in Jquery?
 The attr() method sets or returns attributes and values of the selected elements.
 When this method is used to return the attribute value, it returns the value of the first matched element.
 When this method is used to set attribute values, it sets one or more attribute/value pairs for the set of matched elements.
$(selector).attr(attribute) //it will return the value of an attribute
 $(selector).attr(attribute,value) //it will set the value of an attribute
 $(selector).attr({attribute:value, attribute:value,...}) //for set multiple attribute

Q-26).Can we use both jQuery and AJAX together?
Ans: yes

Q-27).Tell the name of jQuery method which is used to perform an asynchronous HTTP request?
Ans: jQuery.ajax()
 

Q-28).What is the use of jquery load() method?
 The jQuery load() method is a powerful AJAX method.
 The load() method loads data from a server and puts the returned data into the selected element without reload the complate page.
 Ex:The following example loads the content of the file "demo_test.txt" into a specific <div> element
$("#div1").load("demo_test.txt"); Q-29).Can we use our own specific charactor in the place of $ sigh in Jquery?
Ans: Yes
You can also create your own shortcut very easily. The noConflict() method returns a reference to jQuery, that you can save in a variable, for later use. Here is an example

    var vikas = $.noConflict();

     vikas(document).ready(function () {
         vikas("button").click(function () {
             vikas("p").text("jQuery is still working!");
         });
     });


Q-30).Name the 5 Jquery events?
Ans:-
 jQuery Events
 jQuery click() event.
 jQuery dblclick() event.
 jQuery mouseenter() event.
 jQuery mouseleave() event.
 jQuery mousedown() event.
 jQuery mouseup() event.
 jQuery hover() event.
 jQuery focus() and blur() events.




Q-31).What is difference between jQuery's ready and holdReady?
 jQuery's ready is an event which gets triggered automatically when DOM is ready while holdReady is a signal/flag to hold this triggering. holdReady was included in 1.6 version and it works only if used before the execution/triggering of ready event. Once ready event is fired, it has nothing to do. It is useful in dynamically loading scripts before the ready starts. It release ready event execution when used with a true parameter.
 

Q-32).What is Jquery $.ajax() method?
 The Jquery ajax() method is used to perform an AJAX (asynchronous HTTP) request.

Q-33).Name any four paremeter of Jquery ajax method?
 url : Specifies the URL to send the request to. Default is the current page
 type : Specifies the type of request. (GET or POST)
 data : Specifies data to be sent to the server
 cache: A Boolean value indicating whether the browser should cache the requested pages. Default is true beforeSend(xhr): A function to run before the request is sent

Q-34).When can you use jQuery?
 JQuery can be used to perform
 1.Call methods on specific events
 2.Traverse the documents
 3.For apply CSS
 4.Manipulation purpose and
 5.To add effects too.
 6.For apply animations
 7.For give atractive look (dialogbox etc)
 8.For asynchronous calls ($.ajax())

Q-35).What is the use of noConflict() method in Jquery?

Q-36).How to select combobox selecte value and text using Jquery?
 Example:
var StateID = $("#StateCbx").val(); // Or you can use it $("#iStateID").val();
var StateName = $("#StateCbx option:selected").text();
alert("Selected combobox text is= " + StateName + " and value is= " + StateID);

Q-37).JQuery html() method works for both HTML and XML documents?
 No, It only works for HTML

Q-38).Can you call C# codebehind method using Jquery?
 Yes

Q-39).How can you call a method inside code-behind using jQuery?
 By $.ajax and by declaring method a WebMethod

Q-40).What is the use of jQuery.data()?
 jQuery’s data method gives us the ability to associate arbitrary data with DOM nodes and JavaScript objects. This makes our code more concise and clean.
 For live example click here
 http://tutorialzine.com/2010/11/jquery-data-method/

Q-41).Is jQuery a W3C standard?
 No

Q-42).What is the use of jquery .each() function?
 Basically, the jQuery .each() function is used to loop through each element of the target jQuery object. Very useful for multi element DOM manipulation, looping arrays and object properties.
 Example:-
 In this example alert box will open 3 times because dom contain 3 <li> tags

<script>
    $(document).ready(function () {
        $("button").click(function () {
            $("li").each(function () {
                alert($(this).text())
            });
        });
    });
 </script>

 <ul>
 <li>Coffee</li>
 <li>Milk</li>
 <li>Soda</li>
 </ul>


Q-43).If you have a server control(asp.net server control, Button) and on the click of button you want to call a jquery function, So how you will call a jquery function without postback?
 ASP.NET provides the OnClientClick property to handle button clicks. You can use this property on Button, LinkButton and ImageButton. The same OnClientClick property also allows you to cancel a postback.
 So I can use OnClientClick property and Jquery function will return false.
 Example
<script type="text/javascript">
    function callMe() {
        alert('Hello');
        return false;
    }
 </script>
 <asp:Button ID="Button1" runat="server" OnClientClick="return callMe();"Text="Button" />


Q-44).What is the use of .Size() method in Jquery?
 Jquery's .size() method returns number of element in the object. That means that you can count the number of elements within an object.
 

Q-45).What is the difference between jquery.size() and jquery.length?
 Jquery.size() and jquery.length both returns the number of element found in the object. But, jquery.length is faster than jquery.size() because size() is a method but length is a property.

Q-46).How you can debug Jquery code/What are the technique to debug jquery?
 Add the keyword "debugger;" to the line from where we want to start the debugging and then run the Visual Studio in Debug mode by pressing F5 or using the Debug button.

Q-47).Difference between jQuery-x.x.x.js and jQuery.x.x.x min.js?
 jQuery-x.x.x.js = Pretty and easy to read Smile Read this one.
 jQuery.x.x.x min.js = Looks like jibberish! But has a smaller file size. Put this one on your site for fast loading and less size.

Q-48).How to get the server response from an AJAX request using Jquery?
 When invoking functions that have asynchronous behavior We must provide a callback function to capture the desired result. This is especially important with AJAX in the browser because when a remote request is made, it is indeterminate when the response will be received.
 
Below an example of making an AJAX call and alerting the response (or error):
     $.ajax({
         url: 'pcdsEmpRecords.php',
         success: function (response) {
             alert(response);
         },
         error: function (xhr) {
             alert('Error! Status = ' + xhr.status);
         }
     });


Q-49).Do we need to add the JQuery file both at the Master page and Content page as well?
 No, if the Jquery file has been added to the master page then we can access the content page directly without adding any reference to it.
 
 This can be done using this simple example
 
<script type="text/javascript" src="jQuery-1.4.1-min.js"></script>

Q-50).Difference between onload() and document.ready() function used in jQuery?
 We can add more than one document.ready() function in a page.
 we can have only one onload function.
 Document.ready() function is called as soon as DOM is loaded.
 body.onload() function is called when everything (DOM, images)gets loaded on the page.
 


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