Answer 1

function test() {
    let arr = Array.from({ length: 10 }).map(key => Math.ceil(Math.random() * 10));
    arr = Array.from(new Set(arr)).sort((a, b) => a - b);
    let i = 0, len = arr.length, result = [], temp = [];
    while (i < len) {
        if (temp.length) {
            if (arr[i] === (+temp.slice(-1) + 1)) {
                temp.push(arr[i]);
            } else {
                result.push(temp);
                temp = [arr[i]];
            }
        } else {
            temp.push(arr[i])
        }
        if (i === len - 1) {
            result.push(temp);
        }
        i++;
    }
    return result;
}