It is ionic..
an ionic compound is composed of cation and anion and by electrostatic attraction force. But after formation cation attracts the electron pair towards itself and cause some deformation of electron density of anion. Thus some covalency arises (Fajans’ Rule).
Above all if the ionic character predominates over covalent character, then we call it ionic., and NaH is ionic.
1 5 1
If nah is made from metal & non metal ,their realation will be ionic .,...............& when it is made from 2non metal then their realation is covalent