我已经编写了一个测试脚本来评估用户shekhardtu(见答案)和FurkanO(见答案)提出的两种最通用的解决方案的性能(意味着输入不需要事先排序，代码不依赖于第三方库)。

http://playcode.io/316025?tabs=console&script.js&output

FurkanO的解决方案似乎是最快的。

/* ** performance test for https://stackoverflow.com/questions/18017869/build-tree-array-from-flat-array-in-javascript */ // Data Set (e.g. nested comments) var comments = [{ id: 1, parent_id: null }, { id: 2, parent_id: 1 }, { id: 3, parent_id: 4 }, { id: 4, parent_id: null }, { id: 5, parent_id: 4 }]; // add some random entries let maxParentId = 10000; for (let i=6; i<=maxParentId; i++) { let randVal = Math.floor((Math.random() * maxParentId) + 1); comments.push({ id: i, parent_id: (randVal % 200 === 0 ? null : randVal) }); } // solution from user "shekhardtu" (https://stackoverflow.com/a/55241491/5135171) const nest = (items, id = null, link = 'parent_id') => items .filter(item => item[link] === id) .map(item => ({ ...item, children: nest(items, item.id) })); ; // solution from user "FurkanO" (https://stackoverflow.com/a/40732240/5135171) const createDataTree = dataset => { let hashTable = Object.create(null) dataset.forEach( aData => hashTable[aData.id] = { ...aData, children : [] } ) let dataTree = [] dataset.forEach( aData => { if( aData.parent_id ) hashTable[aData.parent_id].children.push(hashTable[aData.id]) else dataTree.push(hashTable[aData.id]) } ) return dataTree }; /* ** lets evaluate the timing for both methods */ let t0 = performance.now(); let createDataTreeResult = createDataTree(comments); let t1 = performance.now(); console.log("Call to createDataTree took " + Math.floor(t1 - t0) + " milliseconds."); t0 = performance.now(); let nestResult = nest(comments); t1 = performance.now(); console.log("Call to nest took " + Math.floor(t1 - t0) + " milliseconds."); //console.log(nestResult); //console.log(createDataTreeResult); // bad, but simple way of comparing object equality console.log(JSON.stringify(nestResult)===JSON.stringify(createDataTreeResult));

我已经编写了一个测试脚本来评估用户shekhardtu(见答案)和FurkanO(见答案)提出的两种最通用的解决方案的性能(意味着输入不需要事先排序，代码不依赖于第三方库)。

http://playcode.io/316025?tabs=console&script.js&output

FurkanO的解决方案似乎是最快的。

/* ** performance test for https://stackoverflow.com/questions/18017869/build-tree-array-from-flat-array-in-javascript */ // Data Set (e.g. nested comments) var comments = [{ id: 1, parent_id: null }, { id: 2, parent_id: 1 }, { id: 3, parent_id: 4 }, { id: 4, parent_id: null }, { id: 5, parent_id: 4 }]; // add some random entries let maxParentId = 10000; for (let i=6; i<=maxParentId; i++) { let randVal = Math.floor((Math.random() * maxParentId) + 1); comments.push({ id: i, parent_id: (randVal % 200 === 0 ? null : randVal) }); } // solution from user "shekhardtu" (https://stackoverflow.com/a/55241491/5135171) const nest = (items, id = null, link = 'parent_id') => items .filter(item => item[link] === id) .map(item => ({ ...item, children: nest(items, item.id) })); ; // solution from user "FurkanO" (https://stackoverflow.com/a/40732240/5135171) const createDataTree = dataset => { let hashTable = Object.create(null) dataset.forEach( aData => hashTable[aData.id] = { ...aData, children : [] } ) let dataTree = [] dataset.forEach( aData => { if( aData.parent_id ) hashTable[aData.parent_id].children.push(hashTable[aData.id]) else dataTree.push(hashTable[aData.id]) } ) return dataTree }; /* ** lets evaluate the timing for both methods */ let t0 = performance.now(); let createDataTreeResult = createDataTree(comments); let t1 = performance.now(); console.log("Call to createDataTree took " + Math.floor(t1 - t0) + " milliseconds."); t0 = performance.now(); let nestResult = nest(comments); t1 = performance.now(); console.log("Call to nest took " + Math.floor(t1 - t0) + " milliseconds."); //console.log(nestResult); //console.log(createDataTreeResult); // bad, but simple way of comparing object equality console.log(JSON.stringify(nestResult)===JSON.stringify(createDataTreeResult));

一个更简单的从列表到树的函数

NPM安装列表到树精简版

listToTree(列表)

来源:

function listToTree(data, options) {
    options = options || {};
    var ID_KEY = options.idKey || 'id';
    var PARENT_KEY = options.parentKey || 'parent';
    var CHILDREN_KEY = options.childrenKey || 'children';

    var tree = [],
        childrenOf = {};
    var item, id, parentId;

    for (var i = 0, length = data.length; i < length; i++) {
        item = data[i];
        id = item[ID_KEY];
        parentId = item[PARENT_KEY] || 0;
        // every item may have children
        childrenOf[id] = childrenOf[id] || [];
        // init its children
        item[CHILDREN_KEY] = childrenOf[id];
        if (parentId != 0) {
            // init its parent's children object
            childrenOf[parentId] = childrenOf[parentId] || [];
            // push it into its parent's children object
            childrenOf[parentId].push(item);
        } else {
            tree.push(item);
        }
    };

    return tree;
}

斯菲德尔

这是上面的一个修改版本，适用于多个根项，我使用guid为我的id和parentid，所以在创建它们的UI中，我硬编码根项为0000000-00000-00000-TREE-ROOT-ITEM

var树= unflatten(记录，" tree - root - item ");

function unflatten(records, rootCategoryId, parent, tree){
    if(!_.isArray(tree)){
        tree = [];
        _.each(records, function(rec){
            if(rec.parentId.indexOf(rootCategoryId)>=0){        // change this line to compare a root id
            //if(rec.parentId == 0 || rec.parentId == null){    // example for 0 or null
                var tmp = angular.copy(rec);
                tmp.children = _.filter(records, function(r){
                    return r.parentId == tmp.id;
                });
                tree.push(tmp);
                //console.log(tree);
                _.each(tmp.children, function(child){
                    return unflatten(records, rootCategoryId, child, tree);
                });
            }
        });
    }
    else{
        if(parent){
            parent.children = _.filter(records, function(r){
                return r.parentId == parent.id;
            });
            _.each(parent.children, function(child){
                return unflatten(records, rootCategoryId, child, tree);
            });
        }
    }
    return tree;
}

这是我在一个react项目中使用的

// ListToTree.js
import _filter from 'lodash/filter';
import _map from 'lodash/map';

export default (arr, parentIdKey) => _map(_filter(arr, ar => !ar[parentIdKey]), ar => ({
  ...ar,
  children: _filter(arr, { [parentIdKey]: ar.id }),
}));

用法:

// somewhere.js
import ListToTree from '../Transforms/ListToTree';

const arr = [
   {
      "id":"Bci6XhCLZKPXZMUztm1R",
      "name":"Sith"
   },
   {
      "id":"C3D71CMmASiR6FfDPlEy",
      "name":"Luke",
      "parentCategoryId":"ltatOlEkHdVPf49ACCMc"
   },
   {
      "id":"aS8Ag1BQqxkO6iWBFnsf",
      "name":"Obi Wan",
      "parentCategoryId":"ltatOlEkHdVPf49ACCMc"
   },
   {
      "id":"ltatOlEkHdVPf49ACCMc",
      "name":"Jedi"
   },
   {
      "id":"pw3CNdNhnbuxhPar6nOP",
      "name":"Palpatine",
      "parentCategoryId":"Bci6XhCLZKPXZMUztm1R"
   }
];
const response = ListToTree(arr, 'parentCategoryId');

输出:

[
   {
      "id":"Bci6XhCLZKPXZMUztm1R",
      "name":"Sith",
      "children":[
         {
            "id":"pw3CNdNhnbuxhPar6nOP",
            "name":"Palpatine",
            "parentCategoryId":"Bci6XhCLZKPXZMUztm1R"
         }
      ]
   },
   {
      "id":"ltatOlEkHdVPf49ACCMc",
      "name":"Jedi",
      "children":[
         {
            "id":"C3D71CMmASiR6FfDPlEy",
            "name":"Luke",
            "parentCategoryId":"ltatOlEkHdVPf49ACCMc"
         },
         {
            "id":"aS8Ag1BQqxkO6iWBFnsf",
            "name":"Obi Wan",
            "parentCategoryId":"ltatOlEkHdVPf49ACCMc"
         }
      ]
   }
]```

我使用@FurkanO answer并创建了一个可以用于任何对象类型的泛型函数，我还用TypeScript写了这个函数，我更喜欢它，因为它有自动补全功能。

实现:

1. Javascript:

export const flatListToTree = (flatList, idPath, parentIdPath, childListPath, isParent) => {
  const rootParents = [];
  const map = {};
  for (const item of flatList) {
    if (!item[childListPath]) item[childListPath] = [];
    map[item[idPath]] = item;
  }
  for (const item of flatList) {
    const parentId = item[parentIdPath];
    if (isParent(item)) {
      rootParents.push(item);
    } else {
      const parentItem = map[parentId];
      parentItem[childListPath].push(item);
    }
  }
  return rootParents;
};

2. TypeScript:我假设“T”类型有一个属性的孩子列表，你可以改变“childListPath”是一个字符串而不是“keyof T”如果你有不同的用例。

export const flatListToTree = <T>(
  flatList: T[],
  idPath: keyof T,
  parentIdPath: keyof T,
  childListPath: keyof T,
  isParent: (t: T) => boolean,
) => {
  const rootParents: T[] = [];
  const map: any = {};
  for (const item of flatList) {
    if (!(item as any)[childListPath]) (item as any)[childListPath] = [];
    map[item[idPath]] = item;
  }
  for (const item of flatList) {
    const parentId = item[parentIdPath];
    if (isParent(item)) {
      rootParents.push(item);
    } else {
      const parentItem = map[parentId];
      parentItem[childListPath].push(item);
    }
  }
  return rootParents;
};

使用方法:

  const nodes = [
    { id: 2, pid: undefined, children: [] },
    { id: 3, pid: 2 },
    { id: 4, pid: 2 },
    { id: 5, pid: 4 },
    { id: 6, pid: 5 },
    { id: 7, pid: undefined },
    { id: 8, pid: 7 },
  ];
  
  const result = flatListToTree(nodes, "id", "pid", "children", node => node.pid === undefined);