Ajax casually write

 

Step 1

Similar to onkeyup = "usernamechecker (this. Value); call a written JS Function

 

Step 2

In the JS function, execute a call similar to pagemethods. isuseravailable (username, onsucceeded );

 

Step 3

The system will automatically call functions corresponding to the server, such as isuseravailable ()

 

Step 4

In step 2, the written onsucceeded receives some data returned by the server. Automatically assign a value to this JS function, for example
Result…… in function onsucceeded (result, usercontext, methodname ...... The value is automatically assigned.

 

Step 5

OK. After obtaining the return value, you can use it.
If (result = true )............

Reference: http://weblogs.asp.net/traviscollins/archive/2008/02/12/check-username-availability-with-asp-net-ajax.aspx