Javascript 数组按级别排序 [重复]

Question

我在同一数组中有一对多关系的数据。该组织是按级别建立的。元素的父元素总是比其自身高一级，并由parentId引用。

如何从该数组中获取多级数组？最高级别的元素将是主数组，其子元素在javascript中作为子数组？

[{
    _id: 100,
    level: 3,
    parentId: null,
},
{
    _id: 101,
    level: 2,
    parentId: 100,
},
{
    _id: 102,
    level: 2,
    parentId: 100,
},
{
    _id: 103,
    level: 2,
    parentId: 100,
},
{
    _id: 104,
    level: 1,
    parentId: 101,
},
{
    _id: 105,
    level: 1,
    parentId: 102,
},
{
    _id: 106,
    level: 1,
    parentId: 101,
},
{
    _id: 107,
    level: 1,
    parentId: 103,
},
{
    _id: 108,
    level: 1,
    parentId: 102,
},
{
    _id: 109,
    level: 1,
    parentId: 103,
}]

预期产出将是

                       100
                        |
       ------------------------------------
       |                |                 |
      101              102               103
    -------           ------            ------
    |     |           |    |            |    |
   104   106         105  108          107  109

谢谢

Answer 1

您可以使用单个循环将数据制成一棵树。此建议也适用于未排序的数据。

js prettyprint-override">var data = [{ _id: 100, level: 3, parentId: null }, { _id: 101, level: 2, parentId: 100 }, { _id: 102, level: 2, parentId: 100 }, { _id: 103, level: 2, parentId: 100 }, { _id: 104, level: 1, parentId: 101 }, { _id: 105, level: 1, parentId: 102 }, { _id: 106, level: 1, parentId: 101 }, { _id: 107, level: 1, parentId: 103 }, { _id: 108, level: 1, parentId: 102 }, { _id: 109, level: 1, parentId: 103 }],
    tree = function (data, root) {
        var r, o = Object.create(null);
        data.forEach(function (a) {
            a.children = o[a._id] && o[a._id].children;
            o[a._id] = a;
            if (a.parentId === root) {
                r = a;
            } else {
                o[a.parentId] = o[a.parentId] || {};
                o[a.parentId].children = o[a.parentId].children || [];
                o[a.parentId].children.push(a);
            }
        });
        return r;
    }(data, null);

console.log(tree);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

使用Array#duce按节点的id创建一个哈希，然后使用Array.forEach（）迭代数组。如果父id为null，则为根，如果不将其添加到父的子级：

function createTree(data) {
  var tree = [];
  
  data.forEach(function(node) {
    var parentId = node.parentId;
    
    if(parentId === null) {
      tree.push(node);
    } else {
      (this[parentId].children || (this[parentId].children = [])).push(node);
    }
  }, data.reduce(function(hash, node) {
    hash[node._id] = node;
    
    return hash;
  }, Object.create(null)));
  
  return tree;
}

var data = [{
    _id: 100,
    level: 3,
    parentId: null,
},
{
    _id: 101,
    level: 2,
    parentId: 100,
},
{
    _id: 102,
    level: 2,
    parentId: 100,
},
{
    _id: 103,
    level: 2,
    parentId: 100,
},
{
    _id: 104,
    level: 1,
    parentId: 101,
},
{
    _id: 105,
    level: 1,
    parentId: 102,
},
{
    _id: 106,
    level: 1,
    parentId: 101,
},
{
    _id: 107,
    level: 1,
    parentId: 103,
},
{
    _id: 108,
    level: 1,
    parentId: 102,
},
{
    _id: 109,
    level: 1,
    parentId: 103,
}];

var result = createTree(data);

console.log(result);