property Keys[Index: Integer]: string;
Indicates the key part of items that are key-value pairs.
Use Keys to obtain a key part of an item from the list. The Index parameter indicates the index of the key, where 0 is the index of the first item, 1 is the index of the second item, and so on.
You can read the key at a specific index, or use Keys with the Count property to iterate through the list.
This property is read-only.