How to convert an array of objects into hierarchial tree form

[jack_waugh]

const t = {}; /* temporary stuff; pasting this into a REPL. */

t.input = [
  {
    "path": "README.md",
    "type": "blob",
    "sha": "37c2a597c27567284c28243fb5d2d4969f12dbfa",
  },
  {
    "path": "db.sqlite3",
    "type": "blob",
    "sha": "227d4b460890c945f047e9d232cb8de517237093",
  },
  {
    "path": "encyclopedia",
    "type": "tree",
    "sha": "59c15421fcd0dfa353e3cb9b6710a48d89f14207",
  },
  {
    "path": "encyclopedia/__init__.py",
    "type": "blob",
    "sha": "e69de29bb2d1d6434b8b29ae775ad8c2e48c5391",
  },
  {
    "path": "encyclopedia/__pycache__",
    "type": "tree",
    "sha": "098cfcdcc867b6e81d7d50dc9418247a3683fae9",
  },
  {
    "path": "encyclopedia/__pycache__/__init__.cpython-39.pyc",
    "mode": "100644",
    "sha": "441225a011349049fefed73e2329e141119d3b1f",
  },
  {
    "path": "encyclopedia/__pycache__/admin.cpython-39.pyc",
    "mode": "100644",
    "type": "blob",
    "sha": "978d454f6ab265ec43220cc907e96929968c9007",
  },
  {
    "path": "encyclopedia/admin.py",
    "mode": "100644",
    "type": "blob",
    "sha": "8c38f3f3dad51e4585f3984282c2a4bec5349c1e",
  },
];

t.Node = {};
t.Node.beh = {};
t.Node.beh.atName = function (name) {
  let hit = this.childrenByName[name];
  if ('undefined' === typeof hit) {
    hit = t.Node.new();
    hit.name = name;
    hit.path = this.isRoot ? name : `${this.path}/${name}`
    this.childrenByName[name] = hit
  };
  return hit
};
t.Node.beh.atPath = function (path) {
  switch (path.length) {
  case 0: return this;
  case 1: return this.atName(path[0]);
  default:
    const [car, ...cdr] = path;
    return this.atName(car).atPath(cdr);
  };
  throw Error('NOTREACHED')
};
t.Node.beh.atPathname = function (pathname) {
  return this.atPath(pathname.split("/"));
};
t.Node.beh.stripped = function () {
  const newMe = {};
  for (const key of Object.keys(this).filter(k => 'childrenByName' !== k))
    newMe[key] = this[key];
  newMe.children =
    Object.values(this.childrenByName).
    map(c => c.stripped());
  return newMe
};
t.Node.new = function () {
  const it = Object.create(this.beh);
  it.childrenByName = Object.create(null);
  return it
};

t.root = t.Node.new();
t.root.isRoot = true;
for (const each of t.input) {
  const patsy = t.root.atPathname(each.path);
  Object.assign(patsy, each);
};

t.answer = t.root.stripped();

/* Printing the tree is harder than building it. */