Trie树

var transObject = function(tableData, keys) {
let hashTable = {}, res = []
for (let i = 0; i < tableData.length; i++) {
let arr = res, cur = hashTable
for (let j = 0; j < keys.length; j++) {
let key = keys[j], filed = tableData[i][key]
if (!cur[filed]) {
let pusher = {
value: filed
}, tmp
if (j !== (keys.length - 1)) {
tmp = []
pusher.children = tmp
}
cur[filed] = { $$pos: arr.push(pusher) - 1 }
cur = cur[filed]
arr = tmp
} else {
cur = cur[filed]
arr = arr[cur.$$pos].children
}
}
}
return res
}