function combineArrays(arr1, arr2) {
	const res = [];

	if (arr1.length === 0) {
		return explodeArray(arr2);
	}
	if (arr2.length === 0) {
		return explodeArray(arr1);
	}
	arr1.forEach(x1 => {
		arr2.forEach(x2 => {
			res.push([].concat(x1, x2));
		});
	});
	return res;
}
Mix two arrays such that each element of the second array is concatenated
onto each element of the first array.

For example:
combineArrays([a, [b, c]], [x, y]); // -> [[a, x], [a, y], [b, c, x], [b, c, y]]
@param {Array} arr1 The first array to combine.
@param {Array} arr2 The second array to combine.
@returns {Array} A mixture of the elements of the first and second arrays.