Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Jakarta to Alaska as you normally would.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Jakarta Soekarno-Hatta Intl Airport to Anchorage Airport flight would often be abbreviated as a CGK to ANC flight. Ready for more IATA code knowledge? These are related airports for your current travel destination: Fairbanks Airport (FAI), Juneau Intl Airport (JNU), Ketchikan Airport (KTN), Sitka Airport (SIT), Kodiak Airport (ADQ).