select选择默认值

function GoSelect()
      {      
            var value = $("#helpSelect").val(); //预定选择值
            var obj = document.getElementById("obj"); //select下拉框
            if(value == "") return;
            for(var i=0;i<obj.options.length;i++)
            {
                //alert(obj.options[i].innerText);
                if(obj.options[i].innerText.indexOf(value) > -1)
                {
                    obj.options[i].selected = 'selected';
                }
            }
      }