code challenge

var flatten = (theArr) => {
    const result = [];

    var _flatten = (arr) => {
        for (let i = 0; i < arr.length; i++) {
            if (Array.isArray(arr[i])) {
                _flatten(arr[i]);
            } else {
                result.push(arr[i]);
            }
        }
    };
    _flatten(theArr);
    return result;
};



console.log(flatten([0, [1, 2]]));

console.log(flatten(['a', {b: 1}, [2]]));


console.log(flatten([]));

console.log(flatten([[0], 1, [2, [3, 4], 5], [6, 7]]));