family

var familyData = [ { man: 1, woman:10, daughter:6, son:3 }, { man: 4, woman:5, daughter:5, son:2 }, { man: 1, woman:1, daughter:1, son:1 }, { man: 1, woman:1, daughter:1, son:1 }, { man: 1, woman:1, daughter:1, son:1 }, ] var num = 2 familyData.slice(0,num).map(function(members) { for(var name in members) { members[name]-- } return members }).concat(familyData.slice(num))