JQuery Interview Questions & Answers part 2

Q: – How do You disable or enable a form element?

There are two ways to disable or enable form elements.
Set the 'disabled' attribute to true or false:
// Disable #pcds
$('#pcds').attr('disabled', true);
// Enable #pcds
$('#pcds').attr('disabled', false);

Add or remove the 'disabled' attribute:  // Disable #pcds
$("#pcds").attr('disabled', 'disabled');
// Enable #x

Q: – How do you check or uncheck a checkbox input or radio button?

There are two ways to check or uncheck a checkbox or radio button.
Set the 'checked' attribute to true or false.  // Check #pcds
$('#pcds').attr('checked', true);
// Uncheck #pcds
$('#pcds').attr('checked', false);

Add or remove the 'checked' attribute:
// Check #pcds
$("#pcds").attr('checked', 'checked');
// Uncheck #pcds

Q: – What are the advantages of JQuery ?

There are many advantages with JQuery. Some of them are :

. It is more like a JavaScript enhancement so there is no overhead in learning a new syntax.
. It has the ability to keep the code simple, readable, clear and reusable.
. It would eradicate the requirement for writing complex loops and DOM scripting library calls.

Q: – Why jQuery?

jQuery is very compact and well written JavaScript code that increases the productivity of the developer by enabling them to achieve critical UI functionality by writing very less amount of code.

It helps to

# Improve the performance of the application
# Develop most browser compatible web page
# Implement UI related critical functionality without writing hundreds of lines of codes
# Fast
# Extensible – jQuery can be extended to implement customized behavior

Other advantages of jQuery are

# No need to learn fresh new syntax's to use jQuery, knowing simple JavaScript syntax is enough
# Simple and Cleaner code, no need to write several lines of codes to achieve complex functionality.

Q: – How to use jQuery?

jQuery usually comes as a single JavaScript file containing everything comes out of the box with jQuery. It can be included within a web page using the following mark-up:

To load local jQuery file

<script type="text/javascript" src="jQuery-1.4.1-min.js"></script>

Ideally this markup is kept in under <head></head> tag of your web page, however you are free to keep anywhere you want.

Q: – What is JQuery UI?

JQuery UI is a library which is built on top of JQuery library. JQuery UI comes with cool widgets, effects and interaction mechanism.

Q: – 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

Q: – Which version of jQuery file should be used?

In most of the recent releases so far, the core functionality of jQuery remains same however some more cool and better features are added. Ideally you should use the latest jQuery files available on the jQuery.com website. By doing this you ensure that your earlier functionality will still work and you can use new features available as part of the new release.

Q: – What if the latest jQuery version is available and I am still referring older version of jQuery file from CDNs?

Do not worry about it, it?s a general promise made by CDNs that they will remain hosting the older version of the files on the same location where they had initially released; so even if newer version of the files are released, the older version remains there on the CDNs and your web page still works.

Q: – 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>

Submitted By:-Uma           Email-ID: – kumariuma44@yahoo.in