let someObject = {
  a: {
    b: {
      e: {}
    },
    c: {},
    d: {},
  },
};

const printAllKeys = (obj) => {
  if (typeof obj === 'object') {
    const keys = Object.keys(obj);

    keys.forEach((key) => {
      console.log(key);

      printAllKeys(obj[key]);
    });
  }
};

printAllKeys(someObject);