I'm wondering if some of you missed (or misunderstood, or perhaps I've misunderstood) the OP. Diversion further than intended, not diversion along / relatively near your flight path.

Though given OP's route NRT-JFK and with the diversion being NRT-IAD, the difference between the two is negligible. JFK-IAD is only 228 NM.

The examples of DAL-LIT diverting to MEM and TUL to IAH diverting to MSY and BRO are certainly out of the way / farther than expected.

The others are barely out of the way. I think the most common diversions would be on ETOPS flights over vast stretches of ocean. Like JNB-PER. What would be the most common mid point diversions if necessary?