There have been much discussion in the TC39 subgroup about the meaning of a member lookup operation.
Numerous considerations intersect here.
We will express a general unqualified member lookup operation as a . We will also consider qualified member lookup operations and write them as a . In almost all cases we will be interested in the dynamic type Td of a . In one scheme we will also consider the static type Ts of the expression a . In the simplest approach, we treat an object as merely an association table of member names and member values.