asp.net代碼塊

<form id="form1" runat="server">
    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
    <asp:Button ID="Button7" runat="server" OnClick="Button7_Click" OnClientClick="javascript:return checkForm()"  Text="提交" />
</form>

Javascript代碼塊

<script language="javascript" type="text/javascript">

        function checkForm() {
            if (document.form1.TextBox1.value == "") {
                alert("怎么是空的!");
                document.form1.TextBox1.focus();
                return false;
            }
            var length = document.form1.TextBox1.value.length;
            if (length < 6 || length > 10) {
                alert("必須是6~10個字符內！");
                return false;
            }
        }
   
    </script>