I am using the Alpha Vantage API to get stock market data. The data is returned in this format:

For charting purposes, I need to create an array or object of all of the dates. They are not within the actual data objects so I'm not sure how to do this.
For example, for this specific data I would want an array that looks something like this:
['2021-04-26', '2021-04-26', '2021-04-26', '2021-04-26', '2021-04-26', '2021-05-03'...]
Thanks for the help!