JavaScript数组按级别排序
我们在同一数组中具有一对多关系的数据。该组织是按级别建立的。元素的父级始终比其自身高一级，并由parentId引用。
我们需要从该数组获取多级数组。具有最高级别的元素将是主数组，其子元素为子数组。
如果输入数组由-给定
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，输出结构应类似于-
100
|
------------------------------------
| | |
101 102 103
------- ------ ------
| | | | | |
104 106 105 108 107 109示例
为此的代码将是-
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));输出结果
控制台中的输出将是-
{
"_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
}
]
}
]
}