Nested reading of a json structure using Node.js

read-json.js

const fs = require('fs');
var total = 0

fs.readFile('lists.json', 'utf8', function (err, data) {
  if (err) throw err;
  obj = JSON.parse(data);

  for (var user in obj) {
    console.log('Lists from', user)
    for (var list in obj[user]) {
      lists = obj[user]
      for (var item in lists[list]) {
        items = lists[list]
        if (typeof (items[item]) === 'object') {
          total += Object.keys(items[item]).length
        }
      }
    }
    console.log(total)
    total = 0
  }
});