递归的使用：1.将平铺数组转为树 2.将树转化为平铺数组

平铺数组

    const flatData= [
	    {
    id: '1', parentId: 'root', name:'1'},
	    {
    id: '1-1', parentId: '1', name:'1-1'},
	    {
    id: '1-2', parentId: '1', name:'1-2'},
	    {
    id: '1-1-1', parentId: '1-1', name:'1-1-1'},
	    {
    id: '1-1-2', parentId: '1-1', name:'1-1-2'},
	    {
    id: '1-2-1', parentId: '1-2', name:'1-2-1'}
	];

树形数组targetData

const targetData=[
	 {
    
	 	id: '1', 
	 	parentId: 'root', 
	 	name:'1',
	 	children:[
	 		{
    
	 			id: '1-1', 
	 			parentId: '1', 
	 			name:'1-1',
	 			children:[
			 		{
    
			 			id: '1-1-1', 
			 			parentId: '1-1', 
			 			name:'1-1-1'
			 		},
			 		{
    
			 			id: '1-1-2', 
			 			parentId: '1-1', 
			 			name:'1-1-2'
			 		},
			 	]
	 		},
	 		{
    
	 			id: '1-2',
	 			parentId: '1', 
	 			name:'1-2',
	 			children:[
			 		{
    
			 			id: '1-2-1', 
			 			parentId: '1-2', 
			 			name:'1-2-1'
			 		},
			 	]
	 		},
	 	]
	 },
]

具体代码实现：

1.将平铺数组转为树

关键点: 父亲的id是孩子的parentId

function getTreeData(data,id){
    
    let arr = []
    data.forEach((item,index) => {
    
        let children =  getTreeData(data,item.id)
            if(children.length){
    
                item.children = children
            }
            arr.push(item)
    });
    return arr
}
const treeData= getTreeData(flatData, 'root');
console.log('tree', targetArr);

2.将树转化为平铺数组

let flatData= []
function getFlatData(data){
    
   data.forEach((item,index)=>{
    
        if(item.children&&item.children.length){
    
            getTreeFlatData(item.children)
            delete item.children
        }
        flatData.push(item) 
   })

}
getFlatData(treeData)
console.log(flatData)