These are some of the Very Important Questions that you come across in your Jquery programming life.

1. How to check an element is visible or not using jQuery

Answer: Use Jquery : visible selector
if($("p").is(":hidden")){}
if($("div").is(":hidden")){}

2. How to select an element by name with jQuery?

Answer: This can be acheived by two ways.
WAY 1: by using jquery selector.
Example1: with id $("#foo") Selects all elements with the id="foo".
Example2: SELECTS ALL ELEMENTS $("*") Selects all elements
Example3: SELECTS ALL ELEMENTS WITH CLASS=BAR $(".bar") Selects all elements with class=bar.
Example4: SELECT ALL P ELEMENTS $("p") Selects all P elements
Example5: SELECT P ELEMENTS WITH BAR CLASS $("p.bar") Selects all elements with the id="foo".
WAY 2: GET ELEMENT BY NAME USING JAVASCRIPT AND PASS IT TO JQUERY selector = document.getElementsByName('nameOfElement'); element = $(selector); eg:- If you want to show or hide an element , then simply do like this element.hide() or element.show()

3. How to add text to an existing div with jquery

Answer: var a = "Hello USMTECHWORLD"; $('#dvscore').before(a);

4. How to add jquery file in View of ASP.Net MVC

Answer:
<script src="~/Scripts/jquery-1.10.2.js">
@Scripts.Render("~/Scripts/somesamples.js")
Inside the somesamples.js file, you can write all the jquery scripts related to your ASP.NET MVC view.

5. What is the use of NoConflict method in jQuery

Answer:
Jquery used $ sign for performing jquery actions.There are other frameworks which uses the same $ sign, for eg:- angular,knockout etc. so if 2 different frameworks uses same $ symbol, then one of them might stop working.In order to prevent this jquery introduces a function called noConflict().You can use your own custom variable to perform jquery action like the below example.

        var j = $.noConflict();
        j(document).ready(function(){
             j("button").click(function(){
                     j("p").text("jQuery Rocks!");
                      });
             });
<p>This is a paragraph.<p>
<button>Click jQuery<button>

6.What is the most used selector in jQuery?

Answer:
The selectors in jquery start with dollar sign and parenthesis$(). The most used selectors in jquery are ID and element. Always use '#' character to select elements by ID. (Eg:- <div>$('#dvscore') <div>)

7.How will you check, which version of jQuery you are using in a website?

Answer:
The command used to check version of jquery that you are using in your website is "$.fn.jquery".This command can be run on the console window of any browser.

8.What is event.preventDefault()?

Answer:
It stops the default action of an element from happening.For eg:-it prevents the submit button from submitting a form,prevents link being clicked.

        document.getElementById("Save").addEventListener("click", function(event){
        event.preventDefault()
        });
The above click event prevents the click event being performed.