I often have to check the name value of a lookup field.
In normal cases one would use the code crmForm.all.new_lookupfield.DataValue.name to retrieve this value.
In case of an ambiguous or failed lookup, this datavalue will be null.
What I found out using the IE Developer toolbar was that this kind of lookups used a <span> element to display this “unresolved” state of a lookup.
Both resolved and unresolved lookups have this Span. The only difference will be the classname. So if you like, you can also filter on the className.
So, to access the Text of this Lookup I could use crmForm.all.metris_blueprintid_d.getElementsByTagName(“span”).outerText