Usage of ～じゃん (～じゃない)?

Question

I'd like to know if I can put ～じゃん at the end of every adjective, if there are any exceptions to that usage, and if it's different from ～じゃない. **Adj (na) + じゃん** > 便利じゃん > 便利だったじゃん > 便利じゃないじゃん > 便利じゃなかったじゃん **Adj (i) + じゃん** > 楽しいじゃん > 楽しかったじゃん > 楽しくないじゃん > 楽しくなかったじゃん Is this possible? Wouldn't the correct way would be 楽しくない instead of 楽しいじゃん? **Verb + じゃん** > あるじゃん > やるじゃん > いるじゃん > くるじゃん > ...

Answer 1

サーフィン楽しいじゃん。サーフィンって楽しいじゃない？are both very similar meaning of “Surfing is fun right? or surfing is fun isn't it?”.　Both meanings of the sentences expect the listener to feel the same as he/she feels. You can add じゃん。じゃない？at the end of sentences after nouns or adjectives or verbs. They are same meaning as using よね。 Example: サーフィン楽しいよね。サーフィンって楽しいよね。それすべるよね。それこわいよね。

Answer 2

　～じゃんat the end of sentence, you often hear in casual conversations among friends and family is a dialect. Many native speakers of Japanese believe it to be a standard Japanese since it is understood by anyone and used in the same way with the word ～ね　（ex. 楽しいね、楽しかったね、楽しくなかったね） I hope this information helps.