How to access a specific property of an object if I don't know its keys?

Question

I get this output from the API:

  'Meta Data': {
    '1. Information': 'Daily Prices (open, high, low, close) and Volumes',
    '2. Symbol': 'ibm',
    '3. Last Refreshed': '2021-01-15',
    '4. Output Size': 'Compact',
    '5. Time Zone': 'US/Eastern'
  },
  'Time Series (Daily)': {
    '2021-01-15': {
      '1. open': '128.2800',
      '2. high': '129.2400',
      '3. low': '127.6700',
      '4. close': '128.3900',
      '5. volume': '4905506'
    },
    '2021-01-14': {
      '1. open': '128.0200',
      '2. high': '130.1600',
      '3. low': '127.5500',
      '4. close': '128.9700',
      '5. volume': '7503180'
    },
    '2021-01-13': {
      '1. open': '129.1500',
      '2. high': '129.7500',
      '3. low': '126.4550',
      '4. close': '126.9200',
      '5. volume': '7677739'
    },
    '2021-01-12': {
      '1. open': '129.0900',
      '2. high': '129.8500',
      '3. low': '127.9400',
      '4. close': '129.2100',
      '5. volume': '3729068'
    },
    '2021-01-11': {
      '1. open': '127.9500',
      '2. high': '129.6750',
      '3. low': '127.6600',
      '4. close': '128.5800',
      '5. volume': '5602466'
    },
    '2021-01-08': {
      '1. open': '128.5700',
      '2. high': '129.3200',
      '3. low': '126.9800',
      '4. close': '128.5300',
      '5. volume': '4676487'
    }
  }
} 

and I need to extract data from the first object in Time Series (Daily), but I have to know the date like this: var price = data["Time Series (Daily)"]["2021-01-15"]["1. open"]; to get back 128.2800

It isn't an array so I can't do something like: var price = data["Time Series (Daily)"][1]["1. open"];

Does anyone how to do it?