treebuilder.js

/* eslint no-console: "off", no-unused-vars: "off" */
var xs = [
  {id: 'A', pid: '', name: 'aaa'},
  {id: 'B', pid: '', name: 'bbb'},
  {id: 'C', pid: '', name: 'ccc'},
  {id: 'A-a', pid: 'A', name: 'aaa-aaa'},
  {id: 'A-b', pid: 'A', name: 'aaa-bbb'},
  {id: 'B-a', pid: 'B', name: 'bbb-aaa'},
  {id: 'B-b', pid: 'B', name: 'bbb-bbb'},
  {id: 'C-a', pid: 'C', name: 'ccc-aaa'},
  {id: 'C-a-a', pid: 'C-a', name: 'ccc-aaa-aaa'},
  {id: 'C-a-a-a', pid: 'C-a-a', name: 'ccc-aaa-aaa-aaa'},
  {id: 'C-a-a-b', pid: 'C-a-a', name: 'ccc-aaa-aaa-bbb'},
  {id: 'C-a-a-c', pid: 'C-a-a', name: 'ccc-aaa-aaa-ccc'},
  {id: 'C-a-b', pid: 'C-a', name: 'ccc-aaa-bbb'},
  {id: 'C-a-c', pid: 'C-a', name: 'ccc-aaa-ccc'},
]

function buildTree(xs, cidKey, pidKey, childrenKey) {
  var walk = function(root, pid) {
    root[childrenKey] = xs
      .filter(function(v) {return v[pidKey] == pid})
      .map(function(parent){return walk(parent, parent[cidKey])})
    return root
  }
  return walk({}, '')[childrenKey]
}

var tree = JSON.stringify(buildTree(xs, 'id', 'pid', 'children'), null, 2)
console.log(tree)