SharePoint - javascript how to validate llokupfield in new form

Hi,
i need to do a validation, a lookupfield "field1", has some items, and i want  when user that is adding new item, select the "counting" choice, an alert to be shown.
i dont know how to do this for look up fields, i have created a new form.

and im using this: var var1 = getTagFromIdentifierAndTitle("SELECT","Lookup","field1");

if you have any idea pls share because it is very urgent to me!

thnx

The code which you are using that will work for normal control  but if you are using LookupField  then try something like this-

Try like this-

var cons = document.getElementsByTagName("select");
for (var i = 0; i < cons.length; i++) {
if (tags[i].title == "field1") {
//your code
}
}


TRy this and let me know.

it does not work.....
can you explain better pls??? fiel1 is the name of field lookup type.

pls i need to get the selected item of field1

if you can help me with the section " //your code "

thnx in advance