let array = [
['test1','test2','test3','test4'], // рандомно перемешалось, пример ('test4','test1','test3','test2')
['test11','test22','test33','test44'],
['test111','test222','test333','test444'],
];
const randomMix = array => {
const mixer = (arr, res = []) => {
if (arr.length === 0) return res;
const randomIndex = Math.floor(Math.random() * arr.length);
const newRes = arr.splice(randomIndex, 1)
return mixer(arr, [...res, ...newRes])
}
return array.map(arr => mixer(arr))
}