创建所有可能的组合-javascript

Question

I'm sorry if this is a duplicate, but I haven't found a solution to my problem. I have 4 groups of words, I need to create all possible combinations of 4, yet keeping group restrictions (ie. there must be a word from each group and no doubling from a group).

Psuedo-code example:

Group1 = [A1, A2]
Group2 = [B1, B2]
Group3 = [C1, C2]
Group4 = [D1, D2]

Result:
A1 B1 C1 D1, 
A2 B1 C1 D1, 
A1 B2 C1 D1 ...

Unacceptable:
A1 A2 B1 C1, 
A1 B1 B2 C1

I really don't even know where to start something like this. Initial groups are arrays.

Thanks in advance.

Answer 1

This should do the trick:

function cartesian() {
    var r = [], arg = arguments, max = arg.length-1; //r=results, arg=the arrays you sent, max=number of arrays you sent
    function helper(arr, i) {// this is a recursive function
        for (var j=0, l=arg[i].length; j<l; j++) { //for 0 to the current array's length
            var a = arr.slice(0); // clone array sent
            a.push(arg[i][j]) // add string
            if (i==max) { // reached 4 elements, add that as possibility
                r.push(a);
            } else // if its not 4, call recursive function sending the current possibility array and the following index of the array to choose from
                helper(a, i+1);
        }
    }
    helper([], 0); // this starts the recursive function, sending an empty array and index 0 (start with nothing from 0)
    return r; // after recursive function ends, return possibilities
};

Group1 = ["A1", "A2"]
Group2 = ["B1", "B2"]
Group3 = ["C1", "C2"]
Group4 = ["D1", "D2"]

console.log(cartesian(Group1,Group2,Group3,Group4));