扁平数组与树状结构的转换

我们在使用后台传过来的数据的时候，有时候我们会得到树状结构的数据，虽然有时候，后端会处理掉，但，毕竟我们也可以在前端给它处理一下，一方面也锻炼一下脑子，天天写页面都没思考能力了。

树状结构转为扁平数组

let tree = {
  id: '1',
  pid: '7',
  name: 'aaaaa',
  children: [
    {
      id: '2',
      pid: '1',
      name: 'bbbbbbb',
      children: [
        {
          id: '6',
          pid: '2',
          name: 'ccccc',
          children: [{ id: '9', pid: '6', name: 'dddd' }],
        },
      ],
    },
  ],
};

const toArray = (tree, children) => {
  let arr = [];
  const a = ls => {
    if (ls instanceof Array) {
      ls.forEach(o => {
        let c = o[children];
        delete o[children];
        arr.push(o);
        a(c);
      });
    }
  };
  tree instanceof Array ? a(tree) : a([tree]);
  return arr;
};
toArray(tree, 'children');
/* [
  { id: '1', pid: '7', name: 'aaaaa' },
  { id: '2', pid: '1', name: 'bbbbbbb' },
  { id: '6', pid: '2', name: 'ccccc' },
  { id: '9', pid: '6', name: 'dddd' }
] */

扁平数组转为树状结构

let array = [
  { id: '1', pid: '7', name: 'aaaaa' },
  { id: '2', pid: '1', name: 'bbbbbbb' },
  { id: '6', pid: '2', name: 'ccccc' },
  { id: '9', pid: '6', name: 'dddd' },
];
const arrayToTree = (arr, id, pid) => {
  if (!id || id == '') {
    return [];
  }
  if (arr instanceof Array) {
    let tree = [];
    let treeMap = {};
    arr.forEach(o => {
      treeMap[o[id]] = o;
    });
    arr.forEach(o => {
      let parent = treeMap[o[pid]];
      if (parent && o[id] != o[pid]) {
        if (!parent.children) {
          parent.children = [];
        }
        parent.children.push(o);
      } else {
        tree.push(o);
      }
    });
    return tree;
  } else {
    return [arr];
  }
};
arrayToTree(array, 'id', 'pid');
/* {
	id: '1',
	pid: '7',
	name: 'aaaaa',
	children: [
		{
			id: '2',
			pid: '1',
			name: 'bbbbbbb',
			children: [
				{
					id: '6',
					pid: '2',
					name: 'ccccc',
					children: [{ id: '9', pid: '6', name: 'dddd' }],
				},
			],
		},
	],
} */

在这里记录是为了以防用的时候找不到，这脑子 😝，万一忘了呢