For dash action due to Fear spell, do you have to use the full movement?

@JeremyECrawford for dash action due to Fear spell, do you have to use the full movement? Can you stop once out of line of sight?

— Lindsey (@lionesslinds) July 28, 2017

A creature frightened by the fear spell checks at the end of its turn whether the caster is out of line of sight, not during the turn. #DnD https://t.co/1yAmyB28Gz

— Jeremy Crawford (@JeremyECrawford) July 28, 2017