最近做一个商城，商城有个分类，后端是node，前端vue，数据库mysql，然后想用nodejs输出无限级分类。一开始想的是嵌套递归查询，发现会有一个先后顺序的问题，也想过async和await，感觉也不靠谱。
想做分类，然后又想可以扩展。
数据库查询出来后，把格式转换了一下。
var arr = [ {"id":1,"name":"手机数码","pid":0}, {"id":2,"name":"家用电器","pid":0}, {"id":3,"name":"美妆护肤","pid":0}, {"id":4,"name":"钟表珠宝","pid":0}, {"id":16,"name":"小米","pid":1}, {"id":17,"name":"华为","pid":1}]完整代码：
router.get('/list',function (req,res) { let sql = 'select id,pid,name,img from table_category' var arr = [] pool.query(sql,(err,result)=>{ result.forEach((item,index)=>{ arr[index]={id:item['id'],name:item['name'],pid:item['pid'],img:config.static_img_url+item['img']} }) res.send(tree(arr)) function tree(data) { var map = {}; data.forEach(function (item) { map[item.id] = item; //这里的ID根据数据库的字段 }); //console.log(map) var val = []; data.forEach(function (item) { var parent = map[item.pid]; //这里是父级ID---pid if (parent) { (parent.children || (parent.children = [])).push(item); } else { val.push(item); } }); return val; } })})输出JSON
[{"id":1,"name":"手机数码","pid":0,"children":[{"id":19,"name":"iPhone","pid":1},{"id":18,"name":"荣耀","pid":1},{"id":20,"name":"vivo","pid":1}]}