数组数据转为树状结构

代码

let arr = [
      { id: 3, parent: 2 },
      { id: 1, parent: null },
      { id: 2, parent: 1 },
    ]

let root= arr.map(i=>{
	let children = arr.filter(j=>j.parent==i.id)
	if(children.length){
		i.children=children
	}
	return i
}).find(item=>item.parent==null)

console.log(JSON.stringify(root,null,2));

结果：