SOURCE

const arr = [
    {state: 0},
    {state: 1},
    {state: 4},
    {state: 2},
    {state: 4},
    {state: 0},
    {state: 3},
]
function group(array, subGroupLength) {
    var index = 0;
    var newArray = [];

    while(index < array.length) {
        newArray.push(array.slice(index, index += subGroupLength));
    }

    return newArray;
}

var groupedCountries = group(arr, 3);
console.log(groupedCountries)