Value of uninitialized EEPROM in ESP8266? In my limited testing it appears that the EEPROM in the Wemos D1 is not initialized to 255 like the specs say is the case for AtMega based Arduinos. In fact, the values look to be more-or-less random. Presumably this is because the ESP8266 doesn't actually contain EEPROM, but instead emulates it using flash. Is there a way to initialize the EEPROM region when flashing?

(This is pretty much the same question as here, which has not been answered.) Since I need only a few bytes of data, I'd prefer not to have to use the SPIFS. 

Update: 

Use case: I'm using the WiFiManager library to select the network to connect a Wemos D1 mini to the web to upload data to Thingspeak. I'd like to use WiFiManager to request the api-key and channel id from the user. However, once the user has entered these, I'd prefer not to make them enter the values again. (The api key is 16 random looking chars and difficult to enter correctly.) This means that the device has to store the values persistently between boots - the main use case for EEPROM. But how do you tell that the values in EEPROM (actually flash on an ESP device) are uninitialized crap, not the previous value? As suggested in the comments, setting flag values in a number of vars make it statistically unlikely to the random values from uninitialized memory. On an AtMega device, unless previously used, the values will be 255 in each byte.
Calculate a checksum for the data and store as part of the data. Recalculate the checksum when you read the (questionable) data back again. If the checksum fails, it's invalid. If it passes, the data is valid to some statistical level of confidence. 

A 16-bit checksum would make false acceptance highly unlikely, but  make it long enough for your own comfort level. What would be the worst consequence of a false acceptance: inconvenience (user has to re-enter a number)? Loss of money or property? Loss of life? Choose the complexity of your solution accordingly.