javascript當中的無限分類

var data = [
        {id:100000, name :"1", pid :0},
        {id:100100, name :"1-1", pid :100000, },
        {id:100101, name :"1-1-1", pid :100100, },
        {id:200000, name :"2", pid :0, }, 
        {id:210000, name :"2-1", pid :200000, },
        {id:211000, name :"2-1-1", pid :210000, },
        {id:211100, name :"2-1-1-1", pid :211000, },
        {id:211110, name :"2-1-1-1-1", pid :211100, },
        {id:211111, name :"2-1-1-1-1-1", pid :211110, }
    ]
    function toTree(data) {
      
        // 刪除 全部 children,以防止屢次調用
        data.forEach(function (item) {
            delete item.children;
        });
        console.log(data)
        // 將數據存儲爲 以 id 爲 KEY 的 map 索引數據列
        var map = {};
        data.forEach(function (item) {
            map[item.id] = item;
        });
        console.log(map);
        var val = [];
        data.forEach(function (item) {
            // 以當前遍歷項，的pid,去map對象中找到索引的id
            var parent = map[item.pid];
            console.log(parent);
            debugger
            // 好繞啊，若是找到索引，那麼說明此項不在頂級當中,那麼須要把此項添加到，他對應的父級中
            if (parent) {
                (parent.children || ( parent.children = [] )).push(item);
                console.log(data,val);

            } else {
                //若是沒有在map中找到對應的索引ID,那麼直接把 當前的item添加到 val結果集中，做爲頂級
                val.push(item);
            }
        });

        return val;
    }

    console.log(toTree(data))