[1, 1, 1, 1],
    [0, 0, 0, 0],
    [1, 0, 0, 1],
    [1, 0, 0, 1],
];



function getRegSize (arr, rows, cols) {

    if(rows < 0 || cols < 0 || rows >= arr.length || cols >= arr[rows].length) {
        return 0;
    }

    if(arr[rows][cols] == 0) {
        return 0;
    }

    var size = 1;
    for(var row = rows - 1; row <= rows + 1; row++) {

        for ( var col = cols - 1; col <= cols + 1; col++) {

            if(row != rows || col != cols) {
                size += getRegSize(arr, row, col);
            }

        }

    }
    return size;
}

function getBiggestReg(arr) {
    var maxReg = 0;

    for (var rows = 0; rows < arr.length; rows++) {

        for (var cols = 0; cols < arr[rows].length; cols++) {

            if(arr[rows][cols] == 1) {
                size = getRegSize(arr, rows, cols);
                maxReg = Math.max(size, maxReg);
            }
        }
    }

    return maxReg;
}


console.log(getBiggestReg(arr));