function arrayFlat(arr) {

  return arr.reduce((pre, cur) => {

    const temp = Array.isArray(cur) ? arrayFlat(cur) : cur;

    return pre.concat(temp);

  }, []);

}

const result = arrayFlat([1, [2, 3], [4, [5, 6, [8]], 7]]);

console.log(result);

// 数组拉平 es6 flat

// const arr = [1, [2, 3], [4, [5, 6, [8]], 7]];

// // console.log(arr.flat());

// console.log(arr.flat(2));

// console.log(arr.flat(3));

// [1, [2, [3]]].flat(Infinity);

// 方法1

function ArrayBreak1(arr) {

  const $arr = [...arr];

  return $arr.sort(() => Math.random() - 0.5);

}

console.log(ArrayBreak1([1, 2, 3, 4, 5, 6]));

// 方法2

function ArrayBreak2(arr) {

  const $arr = [...arr];

  const result = [];

  while ($arr.length) {

    const index = Math.floor(Math.random() * $arr.length);

    result.push($arr[index]);

    $arr.splice(index, 1);

  }

  return result;

}

console.log(ArrayBreak2([1, 2, 3, 4, 5, 6]));