treeEach(xs, fn, options)

遍历树

入参

参数	类型	必填	说明
xs	any[]	是	-
fn	Fn	是
options	IOptions	是

type treeEach = <T>(xs: T[], fn: Fn<T>, options?: IOptions) => T[];

type Fn<T> = (
  // 当前元素
  item: T,
  index: number,
  list: T[],
  // 树层级，top从0开始
  level: number,
  // 父节点，level 0 时为null
  parent: T | null
) => T;

interface IOptions<Key = string> {
  // 后代节点key，默认为 "children"
  childKey?: Key;
  // 是否过滤不存在的节点，过滤类型为 null | undefined
  filterNull?: boolean;
  // 是否过滤为空的节点
  filterEmpty?: boolean;
  // false表示从top开始遍历，true表示从叶节点遍历
  startLeaf?: boolean;
}

示例

// 测试数据
const tree1 = [
  null,
  {
    name: "1",
    children: [
      { name: "1.1", children: null },
      { name: "1.2", children: [{ name: "1.2.1" }] },
      {
        name: "1.3",
        children: [
          {
            name: "1.3.1",
          },
          {
            name: "1.3.2",
          },
        ],
      },
    ],
  },
  {
    name: "2",
    children: [
      {
        name: "2.1",
      },
    ],
  },
];

// 从根节点开始遍历
const strArr: string[] = [];
treeEach(tree1, (x) => {
  if (!x) return x;
  strArr.push(x.name);
  // 注意需要返回 x，否则无法遍历子节点
  return x; 
});
strArr.join("/"); // 1/1.1/1.2/1.2.1/1.3/1.3.1/1.3.2/2/2.1

// 从叶子节点开始遍历
const strArr2: string[] = [];
treeEach(
  tree1,
  (x) => {
    if (!x) return x;
    strArr2.push(x.name);
    return x;
  },
  { startLeaf: true }
);
strArr2.join("/"); // 1.1/1.2.1/1.2/1.3.1/1.3.2/1.3/1/2.1/2