Janeika is of Hebrew origin and means 'Yahweh is gracious'. It's a unique combination of Jane and the Hebrew suffix '-ka', denoting belonging to or having the qualities of.
Janeika was quite popular in the late 80s to mid-90s, with peaks in popularity around 1991 and 1993. However, its usage seems to have declined thereafter, as there's a gap of three years between the last two recorded births.