编辑代码

/**
 * 扁平数组数据
 */
let flatArr = [
	{id:1, title:'标题1', parent_id: 0},
	{id:2, title:'标题2', parent_id: 0},
	{id:3, title:'标题2-1', parent_id: 2},
	{id:4, title:'标题3-1', parent_id: 3},
	{id:5, title:'标题4-1', parent_id: 4},
	{id:6, title:'标题2-2', parent_id: 2}
];

/**
 * 二维扁平数组数据，转树型函数
 * @author WEI.ZHOU
 * @version V1.0.0
 */
function convert(list){
	const result = [];
	const map = list.reduce((pre, cur) => {
		pre[cur.id] = cur;
		return pre;
	}, {});
	for(let item of list){
		if(item.parent_id === 0){
			result.push(item);
			continue;
		}
		if(item.parent_id in map){
			const parent = map[item.parent_id];
			parent.children = parent.children || [];
			parent.children.push(item);
		}
	}
	return result;
}

/**
 * 测试方法
 */
let obj = convert(flatArr);
console.log(obj)