JS得到DropDownList的Value和Text

function CheckSelectNS()
            {            
                var selectText = document.FormStatus.DropDownListLevelSite.options[document.FormStatus.DropDownListLevelSite.selectedIndex].text 
                   //var selectValue = document.getElementById("DropDownListLevelSite").value
                if (selectText.substr(0,1) != "-")  
                {        
                    alert("Please select ns site!");
                    document.getElementById("DropDownListLevelSite").selectedIndex = "0";
                }                
            }