Textbox Validation..

Html Code:

<--h1>Search By Name<--/h1>
    <--ul>
        <--asp:TextBox ID="TextBox1" runat="server" Width="123px"><--/asp:TextBox>
        <--asp:ImageButton ID="ImageButton1" runat="server"
            ImageUrl="~/images/search.JPG" onclick="ImageButton1_Click"
            OnClientClick=" return validate()" Height="21px" Width="29px"/>
    <--/ul>(ex: Obama)

Javascript code:

<--script language="javascript" type="text/javascript">
    function validate(){
        if(document.getElementById("<%=TextBox1.ClientID%>").value=="")
        {
            alert("Please enter an associate name!");
            document.getElementById("<%=TextBox1.ClientID%>").focus();
            return false;
        }
            var digits = "0123456789";
            var temp;
            for(var i = 0; i < document.getElementById("<%=TextBox1.ClientID %>").value.length; i++){
                temp = document.getElementById("<%=TextBox1.ClientID%>").value.substring(i, i + 1);
                if (digits.indexOf(temp) != -1) {
                    alert("Please enter a valid value!");
                    document.getElementById("<%=TextBox1.ClientID%>").focus();
                    return false;
                }
            }
            var charc = "~`!@#$%^&*()_+-=|\"':;{}[]?/><.,*";
            var tempo;
            for(var j = 0; j < document.getElementById("<%=TextBox1.ClientID %>").value.length; j++){
                tempo = document.getElementById("<%=TextBox1.ClientID%>").value.substring(j, j + 1);
                if (charc.indexOf(tempo) != -1) {
                    alert("Please enter a valid value!");
                    document.getElementById("<%=TextBox1.ClientID%>").focus();
                    return false;
                }
            }
            return true;
        }
<--/script>