In js, the tripled = checks for type equality as well as value. If you do "4" == 4 it will return true, but if you do "4" === 4 it will return false. So with undefined you're supposed to do 3.
What this basically does is s3Data will be undefined the first time the user tries to view the abstract. Once the http.get returns the data it will be stored in s3Data so it's no longer undefined.

We only go out to s3 for the abstract once.