JQuery Programmer Interview Questions And Answers

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.
jQuery is not a programming language but a well written JavaScript code. It is a JavaScript code, which do document traversing, event handling, Ajax interactions and Animations.

jQuery can be used in following scenarios:

☛ Apply CSS static or dynamic
☛ Calling functions on events
☛ Manipulation purpose
☛ Mainly for Animation effects

A 'jQuery connect' is a plugin used to connect or bind a function with another function. Connect is used to execute function from any other function or plugin is executed.

Connect can be used by downloading jQuery connect file from jQuery.com and then include that file in the HTML file. Use $.connect function to connect a function to another function.

Following are the basic selectors in jQuery:

► Element ID
► CSS Name
► Tag Name
► DOM hierarchy

jQuery load method is a powerful AJAX method which is used to load the data from a server and assign the data into the element without loading the page.

CDN is abbreviated as Content Distribution network and it is said to be a group of companies in different location with network containing copies of data files to maximize bandwidth in accessing the data.

There are two ways to debug jQuery:

Debugger keyword

► Add the debugger to the line from where we have to start debugging and then run Visual Studio in Debug mode with F5 function key.
► Insert a break point after attaching the process

jQuery data method is used to associate data with DOM nodes and JavaScript objects. This method will make a code very concise and neat.

jQuery is a library used for developing Ajax application and it helps to write the code clean and concise. It also handles events, animation and Ajax support applications.

$.ajax can be called and by declaring WebMethod inside code behind using jQuery.

Following are the advantages of jQuery:

► Just a JavaScript enhancement
► Coding is simple, clear, reusable
► Removal of writing more complex conditions and loops

jQuery is a client scripting.

The four parameters are

► URL - Need to specify the URL to send the request
► type - Specifies type of request(Get or Post)
► data - Specifies data to be sent to server
► Cache - Whether the browser should cache the requested page

jQuery file should be added to the Master page and can use access from the content page directly without having any reference to it.

Some of the effects methods are:

☷ Show()
☷ Hide()
☷ Toggle()
☷ FadeIn() and
☷ FadeOut()

jQuery is needed for the following list:

► Used to develop browser compatible web applications
► Improve the performance of an application
► Very fast and extensible
► UI related functions are written in minimal lines of codes

Browser compatibility of jQuery plugin is an issue and needs lot of time to fix it.

QUnit is used to test jQuery and it is very easy and efficient.

Chaining is used to connect multiple events and functions in a selector.

'NoConflict' method is used to reference a jQuery and save it in a variable. That variable can be used instead of Sign.

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

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

► 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.

► AJAX Support − The jQuery helps you a lot to develop a responsive and feature-rich site using AJAX technology.

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

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

► 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+.

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

Closures are created whenever a variable that is defined outside the current scope is accessed from within some inner scope.

A jQuery Selector is a function which makes use of expressions to find out matching elements from a DOM based on the given criteria. Simply you can say, selectors are used to select one or more HTML elements using jQuery. Once an element is selected then we can perform various operations on that selected element. jQuery selectors start with the dollar sign and parentheses - $().

$('#some-id') selects the single element in the document that has an ID of some-id.