How can I create every combination possible for the contents of two arrays?

Question

I have two arrays:

var array1=[\"A\",\"B\",\"C\"];

var array2=[\"1\",\"2\",\"3\"];

How can I set another array to contain every combinatio

Answer 1

Part II: After my complicated iterative "odometer" solution of July 2018, here's a simpler recursive version of combineArraysRecursively()...

function combineArraysRecursively( array_of_arrays ){

        // First, handle some degenerate cases...

        if( ! array_of_arrays ){
            // Or maybe we should toss an exception...?
            return [];
        }

        if( ! Array.isArray( array_of_arrays ) ){
            // Or maybe we should toss an exception...?
            return [];
        }

        if( array_of_arrays.length == 0 ){
            return [];
        }

        for( let i = 0 ; i < array_of_arrays.length; i++ ){
            if( ! Array.isArray(array_of_arrays[i]) || array_of_arrays[i].length == 0 ){
                // If any of the arrays in array_of_arrays are not arrays or are zero-length array, return an empty array...
                return [];
            }
        }

        // Done with degenerate cases...
        let outputs = [];

        function permute(arrayOfArrays, whichArray=0, output=""){

            arrayOfArrays[whichArray].forEach((array_element)=>{
                if( whichArray == array_of_arrays.length - 1 ){            
                    // Base case...
                    outputs.push( output + array_element );
                }
                else{
                    // Recursive case...
                    permute(arrayOfArrays, whichArray+1, output + array_element );
                }
            });/*  forEach() */
        }

        permute(array_of_arrays);

        return outputs;
        

}/* function combineArraysRecursively() */

const array1 = ["A","B","C"];
const array2 = ["+", "-", "*", "/"];
const array3 = ["1","2"];

console.log("combineArraysRecursively(array1, array2, array3) = ", combineArraysRecursively([array1, array2, array3]) );