Difference between href="#" and href="javascript:void(0)"

href="" will link to the same page as the one you are currently on, effectively refreshing the page. href="#" will not refresh the page, but using the # will make the screen move to the top of the page (it is the browser effectively looking for an anchor with no name, ). javascript:void(0) will prevent anything happening on the link at all.

Returning Multiple Values in JAVASCRIPT

function myFunction() {
  var result = testFunction();
   alert(result[0]);//returns "1"
   alert(result[1]);//returns "2"
   alert(result[2]);//returns "3"
}

//This function returns multiple values(a,b,c) in the form of array.

function testFunction() {

  var a="1",b="2",c="3";
    return [a,b,c]
}

Calling Server Side Method Using jQuery/Ajax

With this post I would show how to call server side method from client side. Here we will use jQuery to utilize the Ajax Capabilities which will help us to get/post data to/from server Asynchronously. There are many methods available to perform an async callback to the server. Here I will show a simple example as in how to call a code behind Webmethod.
For simplicity I would be calling the code behind method on a Button Click. Here is the code:
Aspx markup:

   1: <asp:Button ID="Button1" runat="server" Text="Click" />

   2: <br /><br />

   3: <div id="myDiv"></div>

jQuery:

   1: <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js" type="text/javascript"></script>

   2:   <script type ="text/javascript">

   3:       $(document).ready(function () {

   4:           $('#<%=Button1.ClientID %>').click(function () {

   5:               $.ajax({

   6:                   type: "POST",

   7:                   url: "WebForm1.aspx/ServerSideMethod",

   8:                   data: "{}",

   9:                   contentType: "application/json; charset=utf-8",

  10:                   dataType: "json",

  11:                   async: true,

  12:                   cache: false,

  13:                   success: function (msg) {

  14:                       $('#myDiv').text(msg.d); 

  15:                   }

  16:               })

  17:               return false;

  18:           });

  19:       });

  20:   </script>

Code Behind (C#):

   1: [WebMethod]

   2:    public static string ServerSideMethod()

   3:    {

   4:        return "Message from server.";

   5:    }

In the above code, the aspx markup contains a button on click of which we would call the server side method named ServerSideMethod(). The div would show the message returned from the server. When you run the code above and click the button, it would the div would show the message "Message from server".
If you want to send parameters to your code behind method, you would change the line 8 in the above jQuery code as:

   1: data: "{'param1': 1}"

   2: data: "{'pageNumber' :'1','pageSize' : '10'}",

With the above line I would be sending a parameter with value as 1 to the server side method.
The method would change as:

   1: [WebMethod]

   2:    public static string ServerSideMethod(string param1)

   3:    {

   4:        return "Message from server with parameter:"+param1;

   5:    }

The output will now be:
Message from server with parameter:1
You could also call any webmethod method in your webservice by changing the url in the jQuery as:

   1: url: "WebService1.asmx/ServerSideMethod"

where WebService1 is your webservice and ServerSideMethod is your webmethod in WebService1.
Recently I have seen a lot of questions from members in the asp.net forums asking about how to call Javascript confirm on button click and then based on user selection ie Yes/No process code behind logic.
Here is another example of how to do so:

   1: function MyConfirmMethod() {

   2:         if (confirm('Are your sure?')) {

   3:             $.ajax({

   4:                 type: "POST",

   5:                 url: "WebForm1.aspx/ServerSideMethod",

   6:                 data: "{}",

   7:                 contentType: "application/json; charset=utf-8",

   8:                 dataType: "json",

   9:                 success: function (msg) {

  10:                     $('#myDiv').text(msg.d);

  11:                 }

  12:             });

  13:             return false;

  14:         }

  15:         else {

  16:             return false;

  17:         }

  18:     }

   1: protected void Page_Load(object sender, EventArgs e)

   2:   {

   3:       Button1.Attributes.Add("onclick", "return MyConfirmMethod();");

   4:   }

   5:   [WebMethod]

   6:   public static string ServerSideMethod()

   7:   {

   8:       return "Message from server!";

   9:   }

Above you will see I am calling javascript confirm on the button click. On pressing yes, jQuery calls code behind method ServerSideMethod and returns back the message. You could perform any server side logic/database operations here based on the user response. Note I use return false as it prevents postback to the server.

"IN" operator in LINQ

SQL Query using IN operator

SELECT Members.Name
FROM Members
WHERE Members.ID IN ("1,2,3")

LINQ Query equivalent

string[] str = {"1","2"};

var list = Members.Where(p=> str.Contains(p.ID)).Select(X => X);