http://codereview.stackexchange.com/questions/96096/find-common-elements-in-a-list-of-arrays

solution1.js

var arrays  = [
    [1, 4, 6, 123, 78, 8, 9, 124, 44],
    [44, 6, 9, 123],
    [124, 44, 16, 9, 123]
]

function findCommonElements(arrays) {
    var sorted_arr = arrays.map(function(arr) {
        // sort and remove duplicated elements in each array.
        return arr.sort(function (a, b) {return a - b; }).reduce(function (r_arr, ele) {
            if (r_arr.length == 0 || r_arr[r_arr.length-1] != ele) {
                r_arr.push(ele);
            }
            return r_arr;
        }, []);
    }) //.sort(function(ra, rb) {return ra.length - rb.length; });

    var res = []

    var idxs = sorted_arr.map(function(arr) { return 0; })
    sorted_arr.forEach(function(arr) { console.log(arr); })

    var overflow = false;
    var val = sorted_arr[0][0]

    while(!overflow) {
        // update indexs to get index for element >= max
        console.log("Search:", val)
        found_val = true;
        for (var i = 0; i < sorted_arr.length; i++) {
            // change to binary search shift?
            var j;
            for (j = idxs[i]; j < sorted_arr[i].length, sorted_arr[i][j] < val; j++) {}
            console.log([i, j], "e", sorted_arr[i][j], "v", val);
            if (j < sorted_arr[i].length) {
                if (sorted_arr[i][j] > val) {
                    val = sorted_arr[i][j];
                    idxs[i] = j;
                    found_val = false;
                    break;
                } else {
                    idxs[i] = j + 1;
                    // last element.
                    if (idxs[i] == sorted_arr[i].length) {
                        overflow = true;
                    }
                }
            } else {
                overflow = true;
                break;
            }
        }

        if (found_val) { res.push(val);}
    }
    
    return res;
}

console.log("result:", findCommonElements(arrays))

solution2.js

//for nodejs run with: node.exe --harmony_generators

var arrays  = [
    [1, 4, 6, 123, 78, 8, 9, 124, 44],
    [44, 6, 9, 123],
    [124, 44, 16, 9, 123]
]

var check_all_exists = function (gens, val, count) {
    var cur, gen;

    for (var i = 0; i < count; i++) {
        gen = gens.next().value;
        while((cur = gen.next().value) != undefined && cur < val);
        if (cur > val) {
            gen.next(cur); // push back.
            break;
        }
    }

    return cur == val;
}

function findCommonElements(arr) {
    var res = [];
    var val;

    var array_generators = arrays.map(function(arr) {
        // sort and remove duplicated elements in each array.
        return arr.sort(function (a, b) {return a - b; }).reduce(function (r_arr, ele) {
            if (r_arr.length == 0 || r_arr[r_arr.length-1] != ele) {
                r_arr.push(ele);
            }
            return r_arr;
        }, []);
    }).map(function (arr) {
        // create generators for each array.
        return function* () {
            for (var i = 0; i < arr.length; i++) {
                var a = yield arr[i];
                if (a != undefined) { // deal with push back.
                    yield arr[i]; yield arr[i];
                }
            }
        }();
    });

    // generator to iterate generators.
    var generator_iterator = function* () {
        var next = 0;
        while(true) {
            yield array_generators[next%array_generators.length]
            next = next + 1;
        }
    }();

    // iterate 
    while((val = generator_iterator.next().value.next().value) != undefined) {
        console.log("Search:", val);
        if (check_all_exists(generator_iterator, val, array_generators.length - 1)) {
            console.log("\tfound:", val);
            res.push(val);
        }
    }

    return res;
}

console.log(findCommonElements(arrays))