Questions & Answers about По дороге домой я заеду в супермаркет за хлебом.
По дороге means on the way / while (I’m) on the road.
The noun дорога is in the dative singular (дороге) because по often takes the dative when it means along / by / on (a route):
- по дороге = along the road / on the way
Compare: - по дороге домой = on the way home
- по улице = along the street (dative: улице)
Домой is an adverb of direction meaning (to) home. It doesn’t decline and doesn’t use a preposition.
Compare:
- я иду домой = I’m going home (direction → adverb)
- я дома = I’m at home (location)
- я иду в дом = I’m going into the house (into the building)
So по дороге домой literally is “on the way (to) home.”