树形结构和数组结构互相转换

树形转数组

思路： 一个数组把父节点和子节点都塞入一个一维数组中

 const treeToArray = (tree) => {
    let result = []
    const merge = (tree, childName = "children") => {
      result.push(tree)
      tree[childName].forEach(item => merge(item, childName));
      delete tree[childName]
    }
    merge(tree);
    return result;
}

数组转树组件

思路：先将一位数组里的每个元素都找到子节点，最后忽略pid不为0的节点

最后剩下最顶层节点的数组了

  const arrayToTree = (arr, childName = "children", idKey = "id", pidKey = "pid") => arr.filter(item => {
            item[childName] = arr.filter(item2 => item2[pidKey] == item[idKey])
            return item.pid == 0;
        })