What is Ajax autocompleteextender, Syntax and Properties?

In this article i will explain what is Ajax autocompleteextender? what is the syntax and properties? 

AutoComplete Extender:

AutoComplete is an ASP.NET AJAX extender that can be attached to any TextBox control, and will associate that control with a popup panel to display words that begin with the prefix typed into the textbox.

The dropdown with candidate words supplied by a web service is positioned on the bottom left of the text box.

Syntax:

<ajax:AutoCompleteExtender ID="AutoCompleteExtender1" runat="server" TargetControlID="TextBox1"

            ServicePath="WebService.asmx" MinimumPrefixLength="1" EnableCaching="true" CompletionSetCount="1"

            CompletionInterval="1000" ServiceMethod="GetCityName" OnClientPopulating="ShowProcessImage"

            OnClientPopulated="HideProcessImage">

        </ajax:AutoCompleteExtender>

Properties:

The textbox is linked with an AutoCompleteExtender which is initialized with this code.

1.      TargetControlID - The TextBox control where the user types content to be automatically completed (Ex : txtCountry)

2.      ServiceMethod - The web service method to be called. The signature of this method must match the following:

[System.Web.Script.Services.ScriptService]

public List<string> GetNames(string prefixText)

3.      ServicePath - The path to the web service that the extender will pull the word\sentence completions from.

4.      EnableCaching- Caching is turned on, so typing the same prefix multiple times results in only one call to the web service.

5.      MinimumPrefixLength- Minimum number of characters that must be entered before getting suggestions from the web service.

6.      CompletionInterval - Time in milliseconds when the timer will kick in to get suggestions using the web service.

7.      CompletionSetCount - Number of suggestions to be retrieved from the web service.

8.      OnClientPopulating - This one used to display progress image in textbox during getting the data from database using web service.

9.      OnClientPopulated - This one used to hide progress image in textbox after finishing data retrieval from database.

10.  DelimiterCharacters - Specifies one or more character(s) used to separate words. The text in the AutoComplete textbox is tokenized using these characters and the webservice completes the last token.

11.  FirstRowSelected - Determines if the first option in the AutoComplete list will be selected by default.