Joka families are predominantly Serbs and they are mostly from Hrvatska Kostajnica area , less frequently Croats (also from Hrvatska Kostajnica area ). In the past century, relatively most of Croatian residents bearing this family name were born in Hrvatska Kostajnica area and in Zagreb. In Kosna in Hrvatska Kostajnica area every second inhabitant had the family name Joka.
Prevalence
About 130 people with faimily name Joka live in Croatia today, in 70 households. There were 320 of them in the middle of the past century, and their number decreased significantly. They are located in 10 Croatian counties, in 13 cities and 13 other places, mostly in Zagreb (45), and in Trgovi (25), Kosna (20), Dvor (10) and Grmusani (10) in Hrvatska Kostajnica area.
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 1917 in source List of Dignitaries, Officials and Public Servants of the Kingdom of Croatia-Slavonia.