Ques: 1. How JQuery and JavaScript are different?
Answer:
JQuery simplifies the use of the JavaScript language. JavaScript is a language while JQuery is a library built in the JavaScript language that helps to use the JavaScript language.
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Ques: 2. Can JQuery fulfill the need JavaScript?
Answer:
JQuery is not a replacement of JavaScript. JQuery is a different
library which is written on the top of JavaScript. JQuery is a lightweight
JavaScript library that emphasizes interaction between JavaScript and html.
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Ques: 3. What are the effects methods used in JQuery?
Answer:
JQuery enables us to add effects on a web page. JQuery effects can
be categorized into fading, sliding, hiding/showing and animation effects.
JQuery provides many methods for effects on a web page. These are the effects
methods used in JQuery:
show() - It displays or shows the selected elements.
hide() - It hides the matched or selected elements.
toggle() - It shows or hides the matched elements. In other
words, it toggles between the hide() and show() methods.
fadeIn() - It shows the matched elements by fading it to
opaque. In other words, it fades in the selected elements.
fadeOut() - It shows the matched elements by fading it to
transparent. In other words, it fades out the selected elements.
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Ques: 4. What is the function of ajaxComplete() as JQuery Ajax event method?
Answer:
Whenever an Ajax request completes, JQuery triggers the
ajaxComplete event. Any and all handlers that have been registered with the
.ajaxComplete() method are executed at this time.
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Ques: 5. What is the difference between the ID selector and class selector in
JQuery?
Answer:
ID selector and class selector are the same as they are in CSS. ID
selector uses ID while the class selector uses a class to select elements. You
use an ID selector to select just one element. If you want to select a group of
elements, having the same CSS class, you can use the class selector.
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Ques: 6. What does dollar sign ($) mean in JQuery?
Answer:
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 replace with JQuery keyword.
JQuery(document).ready(function()){
});
Ques: 7. What is the difference between body.onload() and document.ready()
function?
Answer:
Document.ready() function is different from body.onload() function
for 2 reasons:
1. we can have more than one document.ready() function in a page where we can
have only one body.onload() function.
2. document.ready() function is called as soon as DOM is loaded where
body.onload() function is called when everything gets loaded on the page that
includes DOM, images and all associated resources of the page.
Ques: 8. What is JQuery UI?
Answer:
JQuery UI is a set of user interface interactions, effects,
widgets, and themes built on top of the JQuery JavaScript Library. JQuery UI
works well for highly interactive web applications with many controls or for a
simple page with a date picker control.
Ques: 9. What is the advantage of hosting a JQuery using a CDN?
Answer:
CDN stands for Content Delivery Network or Content Distribution
Network. It is a large distributed system of servers deployed in multiple data
centres across the internet. It provides the files from servers at a higher
bandwidth that leads to faster loading time.
Advantages of using CDN are:
· The
JQuery library download time will be reduced. For example - Users in Europe
will hit the CDN in Europe and users in the US will hit the US CDN. As a
result, this will reduce the overall page load time.
· The
JQuery library will already be cached in the user’s browser if the user visited
another website that references the same JQuery library. In this case, the user
need not download the JQuery library.
Ques: 10. What is the difference between find and children methods?
Answer:
Both the methods are used to filter the child of the matched
elements. Find method is used to find all levels down the DOM tree but children
method searches only a single level down the DOM tree.
Ques: 11. What do you understand by JQuery.noConflict?
Answer:
JQuery no-conflict is an option given by JQuery to overcome the
conflicts between the different js frameworks or libraries. When we use JQuery
no-conflict mode, we are replacing the $ to a new variable and assigning to
JQuery some other JavaScript libraries. Also use the $ (Which is the default
reference of JQuery) as a function or variable name what JQuery has. And in our
development life, we are not at all strict to only JQuery.
Ques: 12. Why there are two different version of JQuery library?
Answer:
JQuery library comes in 2 different versions:
1). Production
2). Deployment
The production version is quite useful at development time as JQuery is open
source and if you want to change something then you can make those changes in
production version.
But the deployment version is small version or compressed version
so it is impossible to make changes in it. because it is compressed, so its
size is very less than the production version which affects the page load time.
Ques: 13. Which are the popular JQuery CDN? and what is the advantage of using
CDN?
Answer:
There are 3 popular JQuery CDNs:
1. Google
2. Microsoft
3. JQuery
Advantage of using CDN.
1. It reduces the load from your server.
2. It saves bandwidth. JQuery framework will load faster from these CDN.
3. 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.
Ques: 14. How to remove a DOM Element using JQuery?
Answer:
Sometimes we get a requirement to delete all child nodes and
remove DOM elements using JQuery to make a dynamic web page. In this scenario
JQuery provides a couple of methods to remove DOM elements. Here are the
options:
empty()
remove()
html()
Ques: 15. What are JQuery Events?
Answer:
When we design dynamic web pages, we need to apply some events
such as Mouse Click, for forms submit the form after a button click, change a
color after a click, etc.
So in layman language, events are actions that are used for
dynamic web pages. When we perform these actions on an HTML page, we can do
whatever we want.
We use some event handlers to perform the action. Some important handlers are
bind(), unbind(), blur(), off(), hover(), on(), one(), ready(), trigger() etc.
Ques: 16. What is Grouping?
Answer:
When more than one selector shares the same declaration, they may
be grouped together via a comma-separated list; this allows you to reduce the size
of the CSS (every bit and byte is important) and makes it more readable. The
following snippet applies the same background to the first three heading
elements.h1, h2, h3 {background: red;}
Ques: 17. What do you mean by Semantic HTML?
Answer:
Semantic HTML is a coding style where the tags embody what the
text is meant to convey. In Semantic HTML, tags like <b></b> for
bold, and <i></i> for italic should not be used, reason being they
just represent formatting, and provide no indication of meaning or structure.
The semantically correct thing to do is use <strong></strong> and
<em></em>. These tags will have the same bold and italic effects,
while demonstrating meaning and structure (emphasis in this case).
Ques: 18. What is the difference between eq() and get() methods in JQuery?
Answer:
eq() returns the element as a JQuery object. This method
constructs a new JQuery object from one element within that set and returns it.
That means that you can use JQuery functions on it.
get() return a DOM element. This method retrieves the DOM elements matched by
the JQuery object. But as it is a DOM element and it is not a JQuery-wrapped
object. So JQuery functions can't be used.
Ques: 19. What is difference between prop and attr?
Answer:
attr(): Get the value of an attribute for the first element in the
set of matched elements. Whereas,.prop(): (Introduced in JQuery 1.6) Get the
value of a property for the first element in the set of matched elements.
Attributes carry additional information about an HTML element and come in
name="value" pairs. Where Property is a representation of an
attribute in the HTML DOM tree. once the browser parse your HTML code,
corresponding DOM node will be created which is an object thus having
properties.
attr() gives you the value of element as it was defines in the html on page
load. It is always recommended to use prop() to get values of elements which is
modified via javascript/JQuery , as it gives you the original value of an
element's current state. Find out more here.
Ques: 20. Can we execute/run multiple Ajax request simultaneously in JQuery?
Answer:
Yes, it is possible to execute multiple Ajax request
simultaneously or in parallel. Instead of waiting for first ajax request to
complete and then issue the second request is time consuming. The better
approach to speed up things would be to execute multiple ajax request
simultaneously.
Using JQuery.when() method which provides a way to execute callback functions
based on one or more objects, usually Deferred objects that represent asynchronous
events.