JQuery Interview Questions

What is Jquery?
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
Code:
$(document).ready
(function()
{
function body
});

When Jquery founded and by whome?
It was released in January 2006 at BarCamp NYC by John Resig(Jquery founder).

What scripting language is jQuery written in?
Ans: JavaScript

Write a basic code for add jquery library to pages?
Code:

< html >

< head >

< script type="text/javascript" src="jquery.js" >< /script >

< script type="text/javascript" >

< /script >

< /head >

< body >

< a href="http://www.tutoriz.com/">Jquery Interview Questions and Answers < /a>

< /body >

< /html >

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.

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

jQuery uses CSS selectors and XPath expressions to select elements true or false?
Ans:- True

What are the fastest selectors in Jquery?
Ans: ID and element selectors are the fastest selectors.

What are the slower selecoters in Jquery?
Ans: Class selectors are slower

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.

Where Jquery code execute? On client browser or server browser?
Ans: On client browser.

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.
Code:

< 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");

Write the code for select second last div element?
Code for second last div : $("div.questions> div::nth-last-child(2)").css("color", "red");

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.

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

Sample Code 2 (using Chaining)
$(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.

Is jQuery a library for client scripting or server scripting?
Ans: Client Script

What are features of JQuery or What can be done using JQuery?
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

How to check Jquery UI loaded or not?
Ans: // Checking if jQuery UI is loaded or not
Code:
if($.ui){
// jQuery UI is loaded
}else {
// jQuery UI is not loaded
}

How check currently loaded jQuery UI version on the page?
Ans: // Returns jQuery UI version (ex: 1.8.2) or undefined
$.ui.version

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

If you have a table, how you will apply the two differtcolor on alternate rows using Jquery?
Code:
< table border="1">
< tr>< td>VikasAhlawat< /td>< /tr>
< tr>< td>Edwin George< /td>< /tr>
< tr>< td>RohitKhurana< /td>< /tr>
< tr>< td>Gyan Singh< /td>< /tr>
< /table>
Ans :
< script src="jquery.js">< /script>
< script>
$(document).ready(function()
{
$("tr:even").css("background-color", "#f4f4f8");
$("tr:odd").css("background-color", "#ffffff");
});
< /script>

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

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

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.
Code:
$(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

Can we use both jQuery and AJAX together?
Ans: yes

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

What is the use of jquery load() method?
The jQueryload() 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");

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:
Code:
varvikas = $.noConflict();
vikas(document).ready(function(){
vikas("button").click(function(){
vikas("p").text("jQuery is still working!");
});
});

Name the 5 Jquery events?
Ans:-
jQuery Events.
jQueryclick() event.
jQuerydblclick() event.
jQuerymouseenter() event.
jQuerymouseleave() event.
jQuerymousedown() event.
jQuerymouseup() event.
jQuery hover() event.
jQuery focus() and blur() events.