前端面试必问：数组扁平化转换

znhyXYG

于 2022-12-22 14:06:25 发布

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文章标签：前端 javascript 开发语言

本文链接：https://blog.youkuaiyun.com/znhyXYG/article/details/128407426

版权

本文介绍了如何在前端开发中，通过函数`treeToArray`和`arrayToTree`实现树形数据结构与扁平数组之间的转换，以HTML、CSS和JavaScript为例，展示在实际项目中的操作技巧和应用场景。

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let tree = [
  {
    id: 1,
    name: "1",
    pid: 0,
    children: [
      {
        id: 2,
        name: "2",
        pid: 1,
        children: [],
      },
      {
        id: 3,
        name: "3",
        pid: 1,
        children: [
          {
            id: 4,
            name: "4",
            pid: 3,
            children: [],
          },
        ],
      },
    ],
  },
];
// tree形式转为扁平化数组
function treeToArray(tree) {
  let res = [];
  for (const item of tree) {
    const { children, ...i } = item;
    if (children && children.length) {
      res = res.concat(treeToArray(children));
    }
    res.push(i);
  }
  return res;
}
const arr = [
  { id: 1, pid: 0, title: "html" },
  { id: 2, pid: 1, title: "body" },
  { id: 3, pid: 2, title: "div" },
  { id: 4, pid: 2, title: "div" },
  { id: 5, pid: 3, title: "a" },
  { id: 6, pid: 3, title: "a" },
  { id: 7, pid: 5, title: "span" },
];
// 扁平化数组转为tree形式
function arrayToTree(list) {
  let res = [];
  function getChildren(res, pid) {
    for (const item of list) {
      if (item.pid === pid) {
        const newItem = { ...item, children: [] };
        res.push(newItem);
        getChildren(newItem.children, newItem.id);
      }
    }
  }
  getChildren(res, 0);
  return res;
}