JavaScript 数组按级别排序
我们在同一个数组中拥有具有多对一关系的数据。该组织由级别建立。某个元素的父元素始终比其本身高一个级别,并由 parentId 引用。
我们要求从该数组中获取多级数组。级别最高的元素将作为主数组,其子元素作为子数组。
如果给定的输入数组为:
const arr = [ { _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, } ];
然后输出结构应如下所示:
100 | ------------------------------------ | | | 101 102 103 ------- ------ ------ | | | | | | 104 106 105 108 107 109
示例
该代码将是:
const arr = [{ _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, }]; const prepareTree = (arr = [], root = null) => { let res; const obj = Object.create(null); arr.forEach(el => { el.children = obj[el._id] && obj[el._id].children; obj[el._id] = el; if (el.parentId === root) { res = el; } else { obj[el.parentId] = obj[el.parentId] || {}; obj[el.parentId].children = obj[el.parentId].children || []; obj[el.parentId].children.push(el); } }); return res; }; console.log(JSON.stringify(prepareTree(arr), undefined, 4));
输出
控制台中的输出将为:
{ "_id": 100, "level": 3, "parentId": null, "children": [ { "_id": 101, "level": 2, "parentId": 100, "children": [ { "_id": 104, "level": 1, "parentId": 101 }, { "_id": 106, "level": 1, "parentId": 101 } ] }, { "_id": 102, "level": 2, "parentId": 100, "children": [ { "_id": 105, "level": 1, "parentId": 102 }, { "_id": 108, "level": 1, "parentId": 102 } ] }, { "_id": 103, "level": 2, "parentId": 100, "children": [ { "_id": 107, "level": 1, "parentId": 103 }, { "_id": 109, "level": 1, "parentId": 103 } ] } ] }
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