My code cannot be saved to ESP8266

save() does what it says: saving the code (status of the RAM) intoFllash. When you power-cycle, Espruino restores the code (loads the saved state) and invokes onInit() {...} or E.on("init",function(){...}) registered functions. Personally, I prefer the onInit(){...} because no matter of the code load sequence, I get the sequence I want.

If you do not want to power-cycle, invoke/enter onInit(); from with/in the console, and you get your code started. Read through this conversation about simple explanation how to save code that espruino run on start?.