Form validation before onClientClick

function ValidateMe()
{    
    if(!Page_ClientValidate())
    {
        alert("請檢查各欄位是否正確填寫！");
        return true;
    }
    else        
        return false;
}

<asp:Button ID="Button1" runat="server" Text="Submit" OnClientClick="if (!ValidateMe()) return false;" />