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));

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;
}

有同样的问题，但我不能确定数据是否已排序。我不能使用第三方库，所以这只是香草Js;输入数据可以从@Stephen的例子中获取;

var arr = [ {'id':1 ,'parentid' : 0}, {'id':4 ,'parentid' : 2}, {'id':3 ,'parentid' : 1}, {'id':5 ,'parentid' : 0}, {'id':6 ,'parentid' : 0}, {'id':2 ,'parentid' : 1}, {'id':7 ,'parentid' : 4}, {'id':8 ,'parentid' : 1} ]; function unflatten(arr) { var tree = [], mappedArr = {}, arrElem, mappedElem; // First map the nodes of the array to an object -> create a hash table. for(var i = 0, len = arr.length; i < len; i++) { arrElem = arr[i]; mappedArr[arrElem.id] = arrElem; mappedArr[arrElem.id]['children'] = []; } for (var id in mappedArr) { if (mappedArr.hasOwnProperty(id)) { mappedElem = mappedArr[id]; // If the element is not at the root level, add it to its parent array of children. if (mappedElem.parentid) { mappedArr[mappedElem['parentid']]['children'].push(mappedElem); } // If the element is at the root level, add it to first level elements array. else { tree.push(mappedElem); } } } return tree; } var tree = unflatten(arr); document.body.innerHTML = "<pre>" + (JSON.stringify(tree, null, " "))

JS小提琴

平面阵列到树

ES6地图版本:

getTreeData = (items) => {
  if (items && items.length > 0) {
    const data = [];
    const map = {};
    items.map((item) => {
      const id = item.id; // custom id selector !!!
      if (!map.hasOwnProperty(id)) {
        // in case of duplicates
        map[id] = {
          ...item,
          children: [],
        };
      }
    });
    for (const id in map) {
      if (map.hasOwnProperty(id)) {
        let mappedElem = [];
        mappedElem = map[id];
        /// parentId : use custom id selector for parent
        if (
          mappedElem.parentId &&
          typeof map[mappedElem.parentId] !== "undefined"
        ) {
          map[mappedElem.parentId].children.push(mappedElem);
        } else {
          data.push(mappedElem);
        }
      }
    }
    return data;
  }
  return [];
};

/// use like this :

const treeData = getTreeData(flatList);

你可以使用这个来自Github或NPM的“treeify”包。

安装:

$ NPM install——save-dev treeify-js

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"
         }
      ]
   }
]```