complementary

gistfile1.js

function complementary(aArr, bArr) {
    if (bArr.length === 0) {
        return aArr;
    }
    var str = bArr.join(','),
        _a = aArr.concat(bArr).sort();
    _a.sort(function (a, b) {
        if (a === b) {
            var n = str.indexOf(a),
                m = aArr.indexOf(a);
            if (n != -1) {
                aArr.splice(m, 1);
            }
        }
    });

    return aArr;
}