如何用JS高效生成指定长度的自定义数组？

function createlistdata(list, num = 600) {
  let count = list.reduce((n, i) => n + i.test, 0);
  let step = num / count | 0; //向下取整
  let data = list.map((item, index) => {
    return array.from({ length: item.test }).map(citem => {
      return {
        min: 0,
        max: 0,
      };
    });
  });

  let max = math.max(...list.map(i => i.test));
  let value = 0,
    idx = 1;
  for (let index = 0; index < max; index++) {
    data.foreach(item => {
      if (item[index]) {
        item[index].index = idx++;
        item[index].min = value + 1;
        value += step;
        item[index].max = num < value + step ? num : value;
      }
    });
  }

  return data;
}

function createListData(list, num = 600) {
  let count = list.reduce((n, i) => n + i.test, 0);
  let step = num / count | 0; //向下取整
  let value = 0,
    idx = 1;
  let data = list.map((item, index) => {
    return Array.from({ length: item.test }).map(citem => {
      let start = value;
      value += step;
      return {
        index: idx++,
        min: start + 1,
        max: num < value + step ? num : value,
      };
    });
  });

  return data;
}