Questions in: JAVA

Shravya

DOM parser loads whole XML documents in memory while SAX only loads a small part of the XML file in memory. 2) DOM parser is faster than SAX because it accesses the whole XML document in memory. 3) SAX parser in Java is better suitable for a large XML file than DOM Parser because it doesn't require much memory.

The .finish() method stops all queued animations and places the element(s) in their final state. This method was introduced in jQuery 1.9.

The .finish() method is similar to .stop(true, true) in that it clears the queue and the current animation jumps to its end value. It differs, however, in that .finish() also causes the CSS property of all queued animations to jump to their end values, as well.

No. If things can be done easily via CSS or JavaScript then You should not think about jQuery. Remember, jQuery library always comes with xx kilobyte size and there is no point of wasting bandwidth.

It can be done via calling .stop([clearQueue ] [, jumpToEnd ]) method and by passing both the parameters as true.

Well, before jQuery 1.9 release it was not possible but one of the new feature of jQuery 1.9 was .css() multi-property getter.
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var propCollection = $("#dvBox").css([ "width", "height", "backgroundColor" ]);
In this case, the propCollection will be an array and it will look something like this.
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{
width: "100px",
height: "200px",
backgroundColor: "#FF00FF"
}

The latest version (when this post is written) of jQuery is 1.10.2 or 2.0.3. jQuery 2.x has the same API as jQuery 1.x, but does not support Internet Explorer 6, 7, or 8.

No. jQuery 2.0 has no support for IE 6, IE 7 and IE 8.

Yes jQuery 2.0 has supported IE but higher version IE11,IE9 etc not lower version.

In case of jQuery, Source Map is nothing but mapping of minified version of jQuery against the un-minified version. Source map allows to debug minified version of jQuery library. Source map feature was release with jQuery 1.9. Find out more here.

with release of 1.9 version of jQuery, many deprecated methods were discarded and they are no longer available. But there are many sites in production which are still using these deprecated features and it's not possible to replace them overnight. So jQuery team provided with jQuery Migrate plugin that makes code written prior to 1.9 work with it.
So to use old/deprecated features, all you need to do is to provide reference of jQuery Migrate Plugin. Find out more here.

Using below jQuery methods, you can make ajax calls.
load() : Load a piece of html into a container DOM
$.getJSON(): Load JSON with GET method.
$.getScript(): Load a JavaScript file.
$.get(): Use to make a GET call and play extensively with the response.
$.post(): Use to make a POST call and don't want to load the response to some container DOM.
$.ajax(): Use this to do something on XHR failures, or to specify ajax options (e.g. cache: true) on the fly.

By using jQuery post()/ jQuery get(), you always trust the response from the server and you believe it is going to be successful all the time. Well, it is certainly not a good idea to trust the response. As there can be n number of reason which may lead to failure of response.
Where jQuery.ajax() is jQuery's low-level AJAX implementation. $.get and $.post are higher-level abstractions that are often easier to understand and use, but don't offer as much functionality (such as error callbacks). Find out more here.

Deferred and promise are part of jQuery since version 1.5 and they help in handling asynchronous functions like Ajax. Find out more here.

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. Find out more here.

Yes. We can call C# code-behind function via $.ajax. But for do that it is compulsory to mark the method as WebMethod.

Using jQuery.browser property, we can write browser specific code. This property contains flags for the useragent, read from navigator.userAgent. This property was removed in jQuery 1.9.

Yes. jQuery can be used for making ajax request.

Caching is an area which can give you awesome performance, if used properly and at the right place. While using jQuery, you should also think about caching. For example, if you are using any element in jQuery more than one time, then you must cache it. See below code.
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$("#myID").css("color", "red");
//Doing some other stuff......
$("#myID").text("Error occurred!");
​
Now in above jQuery code, the element with #myID is used twice but without caching. So both the times jQuery had to traverse through DOM and get the element. But if you have saved this in a variable then you just need to reference the variable. So the better way would be,
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var $myElement = $("#myID").css("color", "red");
//Doing some other stuff......
$myElement.text("Error occurred!");
​
So now in this case, jQuery won't need to traverse through the whole DOM tree when it is used second time. So in jQuery, Caching is like saving the jQuery selector in a variable. And using the variable reference when required instead of searching through DOM again.

There could be many reasons for this.
You have forgot to include the reference of jQuery library and trying to access jQuery.
You have include the reference of the jQuery file, but it is after your jQuery code.
The order of the scripts is not correct. For example, if you are using any jQuery plugin and you have placed the reference of the plugin js before the jQuery library then you will face this error.
Find out more here.

Well, it is quite possible that the jQuery plugins which are used are dependent on older version but for your own jQuery code, you would like to use newer version. So because of this dependency, multiple version of jQuery may required sometimes on single page.
Below code shows how to include multiple version of jQuery.
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<script type='text/javascript' src='js/jquery_1.9.1.min.js'></script>
<script type='text/javascript'>
var $jq = jQuery.noConflict();
</script>
<script type='text/javascript' src='js/jquery_1.7.2.min.js'></script>
By this way, for your own jQuery code use "$jq", instead of "$" as "$jq" refers to jQuery 1.9.1, where "$" refers to 1.7.2.