JQuery Interview Questions Part -1

1)What is the use of Delegate() Method in jQuery?
Ans)
The delegate() method can be used in two ways.
1) If you have a parent element, and you want to attach an event to each one of its child elements, this delegate() method is used.
Ex:Un-ordered List
Instead of attaching an event to each

element, you can attach a single event to element.
Example:
$("ul").delegate("li", "click", function(){
$(this).hide();
});
2) When an element is not available on the current page, this method is used.
.live() method is also used for the same purpose but, delegate() method is a bit faster.
Example:
$("ul").live("li", "click", function(){
$(this).hide();
});
This will hide any list items that are not currently available on the page. They may be loaded via an Ajax request and then append to it.
Using .bind() or .click() methods, you would have to manually attach events to these new list items once they are added.
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2)Can we select a element having a specific class in jQuery ?
Ans)
Yes, we can select an element with a specific class, we use the class selector.The class name must contain the prefix as "." (dot).


<script language="javascript" type="text/javascript">
$(".class1").css("border", "2px solid red");
</script>

Above code will select all the elements of the webpage containing the class as "class1" and apply the css style border width as 2 Pixel, style as solid and color as red.

What is the basic difference between "var" keyword in Javascript and C# ?

Answer:

In C#, we have "dynamic" keyword. This dynamic keyword is somewhat similar to javascript's "var" . Here, both create a variable whose type will not be known until runtime, and whose misuse will not be discovered until runtime. C#'s var creates a variable whose type is known at compile time.

For example:-

dynamic dt= new DateTime();

dt.bar();


//compiles fine but gives an error at runtime

Tags : var keyword in c#,Jquery

Is it good to load jquery from CDN(Content delivery network)

Answer: Yes, it is always good to load your jquery from content delivery network. It provides some benefits like :-
 (1) Caching - It means that if any previously visited site by user is using jQuery from Google CDN then the cached version will be used. It will not be downloaded again.
 (2) Reduces load - It reduces the load on your web server as it downloads from Google server's.
 Example :-
<script  type="text/javascript"

    src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js">

</script>