longest_ones_sequence.js

function longest_ones_sequence(m) {
    for (
        var r = m.length - 1, c = m[0].length - 1;
        r >= 0 && c >= 0;
        m[r][c] === '1' ? c-- : r--
    );
    return m[0].length - c - 1;
}

console.log(
    longest_ones_sequence(
        [
            "0 0 1 1 1 1 1 1",
            "0 0 0 0 0 0 0 0",
            "0 1 1 1 1 1 1 1",
            "0 0 0 0 0 0 1 1",
            "0 0 1 1 1 1 1 1"
        ].map(function (s) {
            return s.split(' ')
        })
    )
);