[JavaScript知识库]JS 将扁平结构数据结构转树形结构数据

let items = [
	{ id: 1, pid: 0, name: '数据1' },
	{ id: 2, pid: 1, name: '数据2' },
	{ id: 3, pid: 1, name: '数据3' },
	{ id: 4, pid: 3, name: '数据4' },
	{ id: 5, pid: 4, name: '数据5' },
	{ id: 6, pid: 0, name: '数据6' },
]

console.log(itemsToTreeOne(items))
//console.log(itemsToTreeTwo(items))



//第一种方法
function itemsToTreeOne (items) {
	let obj = { }
	let len = items.length
	let resultTree = [ ]
	
	for(i = 0; i < len; i++) {
		if (obj['id' + items[i].id] === undefined) {
			obj['id' + items[i].id] = items[i]
		} else {
			Object.assign(obj['id' + items[i].id], items[i])
		}
		
		if (items[i].pid === 0) {
			resultTree.push(obj['id' + items[i].id])
		} else {
			if (obj['id' + items[i].pid] === undefined) {
				obj['id' + items[i].pid] = { children: [ ] }
			}
			if (obj['id' + items[i].pid].children === undefined) {
				obj['id' + items[i].pid].children = [ ]
			}
			obj['id' + items[i].pid].children.push(items[i])
		}
	}
	
	return resultTree
}



//第二种方法
function itemsToTreeTwo (items) {
	let obj = { }
	let len = items.length
	
	for(i = 0; i < len; i++) {
		obj['id' + items[i].id] = items[i]
		obj['id' + items[i].id].children = [ ]
	}
	
	let resultTree = [ ]
	for(i = 0; i < len; i++) {
		if (items[i].pid === 0) {
			resultTree.push(obj['id' + items[i].id])
		} else {
			obj['id' + items[i].pid].children.push(items[i])
		}
	}
	
	return resultTree
}