题目: 数组转树
比如将下面的input
转换成output
结构
input:
let input = [
{
id: 1,
val: "学校",
parentId: null,
},
{
id: 2,
val: "班级1",
parentId: 1,
},
{
id: 3,
val: "班级2",
parentId: 1,
},
{
id: 4,
val: "学生1",
parentId: 2,
},
{
id: 5,
val: "学生2",
parentId: 2,
},
{
id: 6,
val: "学生3",
parentId: 3,
},
];
output
let output = {
id: 1,
val: "学校",
children: [
{
id: 2,
val: "班级1",
children: [
{
id: 4,
val: "学生1",
children: [],
},
{
id: 5,
val: "学生2",
children: [],
},
],
},
{
id: 3,
val: "班级2",
children: [
{
id: 6,
val: "学生3",
children: [],
},
],
},
],
};
方法,确定根节点之后,利用递归来构造children。
代码如下:
function toTree(arr) {
const root = arr[0];
arr.shift(); // 剔除根节点
return {
id: root.id,
val: root.val,
children: arr.length > 0 ? getChildren(arr, root.id) : [], //只有根节点就不遍历了
};
}
//递归获取子节点
function getChildren(arr, parentId) {
let children = [];
arr.forEach((item) => {
if (item.parentId === parentId) {
children.push({
id: item.id,
val: item.val,
children: getChildren(arr, item.id),
});
}
});
return children;
}
console.log(toTree(input));
看一下输出的结果: