Prevent user from typing in Ajax AutoComplete TextBox for some time based on condition in JavaScript

Hi nauna,

If user type 3 character then disables the TextBox so that user will not be able to type anything.

Then re-enable the TextBox either after 2 second or  on autocomplete item selection.

Refer below code.

Database

For this example I have used of Northwind database that you can download using the link given below.

Download Northwind Database

HTML

<div>
    <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true">
    </asp:ScriptManager>
    <asp:TextBox ID="txtContactsSearch" runat="server" onkeyup="return StopType(this)"></asp:TextBox>
    <cc1:AutoCompleteExtender ID="AutoCompleteExtender1" runat="server" EnableCaching="false"
        MinimumPrefixLength="1" TargetControlID="txtContactsSearch" ServiceMethod="SearchCustomers"
        CompletionInterval="1000" CompletionSetCount="20" FirstRowSelected="false" OnClientItemSelected="ClientItemSelected">
    </cc1:AutoCompleteExtender>
</div>
<script type="text/javascript">
    function StopType(ele) {
        if (ele.value.length >= 3) {
            ele.setAttribute('disabled', 'disabled');
            setTimeout(function () {
                ele.removeAttribute('disabled');
                ele.focus();
            }, 2000);
        }
    }
    function ClientItemSelected(sender, e) {
        sender._element.removeAttribute('disabled');
    }
</script>

Namespaces

C#

using System.Configuration;
using System.Data.SqlClient;
using System.Web.Script.Services;
using System.Web.Services;

VB.Net

Imports System.Configuration
Imports System.Data.SqlClient
Imports System.Web.Script.Services
Imports System.Web.Services

Code

C#

[ScriptMethod()]
[WebMethod]
public static List<string> SearchCustomers(string prefixText, int count)
{
    using (SqlConnection conn = new SqlConnection())
    {
        conn.ConnectionString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = "select CustomerID, ContactName from Customers where ContactName like @SearchText + '%'";
            cmd.Parameters.AddWithValue("@SearchText", prefixText);
            cmd.Connection = conn;
            conn.Open();
            List<string> customers = new List<string>();
            using (SqlDataReader sdr = cmd.ExecuteReader())
            {
                while (sdr.Read())
                {
                    customers.Add(AjaxControlToolkit.AutoCompleteExtender
                        .CreateAutoCompleteItem(sdr["ContactName"].ToString(), sdr["CustomerID"].ToString()));
                }
            }
            conn.Close();
            return customers;
        }
    }
}

VB.Net

<ScriptMethod()> _
<WebMethod()> _
Public Shared Function SearchCustomers(ByVal prefixText As String, ByVal count As Integer) As List(Of String)
    Using conn As SqlConnection = New SqlConnection()
        conn.ConnectionString = ConfigurationManager.ConnectionStrings("constr").ConnectionString

        Using cmd As SqlCommand = New SqlCommand()
            cmd.CommandText = "select CustomerID, ContactName from Customers where ContactName like @SearchText + '%'"
            cmd.Parameters.AddWithValue("@SearchText", prefixText)
            cmd.Connection = conn
            conn.Open()
            Dim customers As List(Of String) = New List(Of String)()
            Using sdr As SqlDataReader = cmd.ExecuteReader()
                While sdr.Read()
                    customers.Add(AjaxControlToolkit.AutoCompleteExtender _
                                  .CreateAutoCompleteItem(sdr("ContactName").ToString(), sdr("CustomerID").ToString()))
                End While
            End Using
            conn.Close()
            Return customers
        End Using
    End Using
End Function

Screenshot