我的解决方案:

允许双向映射(根到叶，叶到根) 返回所有节点、根节点和叶节点 一次数据传递和非常快的性能 香草Javascript

/**
 * 
 * @param data items array
 * @param idKey item's id key (e.g., item.id)
 * @param parentIdKey item's key that points to parent (e.g., item.parentId)
 * @param noParentValue item's parent value when root (e.g., item.parentId === noParentValue => item is root)
 * @param bidirectional should parent reference be added
 */
function flatToTree(data, idKey, parentIdKey, noParentValue = null, bidirectional = true) {
  const nodes = {}, roots = {}, leaves = {};

  // iterate over all data items
  for (const i of data) {

    // add item as a node and possibly as a leaf
    if (nodes[i[idKey]]) { // already seen this item when child was found first
      // add all of the item's data and found children
      nodes[i[idKey]] = Object.assign(nodes[i[idKey]], i);
    } else { // never seen this item
      // add to the nodes map
      nodes[i[idKey]] = Object.assign({ $children: []}, i);
      // assume it's a leaf for now
      leaves[i[idKey]] = nodes[i[idKey]];
    }

    // put the item as a child in parent item and possibly as a root
    if (i[parentIdKey] !== noParentValue) { // item has a parent
      if (nodes[i[parentIdKey]]) { // parent already exist as a node
        // add as a child
        (nodes[i[parentIdKey]].$children || []).push( nodes[i[idKey]] );
      } else { // parent wasn't seen yet
        // add a "dummy" parent to the nodes map and put the item as its child
        nodes[i[parentIdKey]] = { $children: [ nodes[i[idKey]] ] };
      }
      if (bidirectional) {
        // link to the parent
        nodes[i[idKey]].$parent = nodes[i[parentIdKey]];
      }
      // item is definitely not a leaf
      delete leaves[i[parentIdKey]];
    } else { // this is a root item
      roots[i[idKey]] = nodes[i[idKey]];
    }
  }
  return {roots, nodes, leaves};
}

使用的例子:

const data = [{id: 2, parentId: 0}, {id: 1, parentId: 2} /*, ... */];
const { nodes, roots, leaves } = flatToTree(data, 'id', 'parentId', 0);

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);

数组元素可以以混乱的顺序排列

let array = [ { id: 1, data: 'something', parent_id: null, children: [] }, { id: 2, data: 'something', parent_id: 1, children: [] }, { id: 5, data: 'something', parent_id: 4, children: [] }, { id: 4, data: 'something', parent_id: 3, children: [] }, { id: 3, data: 'something', parent_id: null, children: [] }, { id: 6, data: 'something', parent_id: null, children: [] } ] function buildTree(array) { let tree = [] for (let i = 0; i < array.length; i++) { if (array[i].parent_id) { let parent = array.filter(elem => elem.id === array[i].parent_id).pop() parent.children.push(array[i]) } else { tree.push(array[i]) } } return tree } const tree = buildTree(array) console.log(tree); .as-console-wrapper { min-height: 100% }

使用ES6方法。工作很有魅力

//数据集 //一个顶级注释 Const注释= [{ id: 1、 parent_id:零 }, { id: 2 parent_id: 1 }, { id: 3, parent_id: 1 }, { id: 4 parent_id: 2 }, { id: 5 parent_id: 4 }); Const nest = (items, id = null, link = 'parent_id') => 项目 .filter(item => item[link] === id) .map(item =>({…Item, children: nest(items, Item .id)})); console.log ( 巢(评论) ）

经过多次尝试，我得出了这个结论:

const arrayToTree = (arr, parent = 0) => arr .filter(item => item.parent === parent).map(child => ({ ...child, children: arrayToTree(arr, child.index) }));

   

const entries = [ { index: 1, parent: 0 }, { index: 2, parent: 1 }, { index: 3, parent: 2 }, { index: 4, parent: 2 }, { index: 5, parent: 4 }, { index: 6, parent: 5 }, { index: 7, parent: 6 }, { index: 8, parent: 7 }, { index: 9, parent: 8 }, { index: 10, parent: 9 }, { index: 11, parent: 7 }, { index: 13, parent: 11 }, { index: 12, parent: 0 } ]; const arrayToTree = (arr, parent = 0) => arr .filter(item => item.parent === parent) .map(child => ({ ...child, children: arrayToTree(arr, child.index) })); console.log(arrayToTree(entries));