“~じゃ” and ”~ちゃ” are spoken words resulting in the phonetic change of “ては/では“.
“ては/では“ has two meanings. The first is “if“ and it is similar to “たら“, but it is often used to give the negative comments for the condition that you mention before “ては/では“.
The second is “whenever“ and it is used to describe repetitive actions.
- Ken: If you’re checking the news, can you tell me the weather prediction for Saturday?
ニュースを見ているなら、日曜の天気予報を教えてくれない? - Leo: Let me see, it looks like it’s going to rain this Saturday.
ちょっと待って、今週の日曜は雨になりそうだね。 - Ken: Really? Although we want to compete against ABC team, we can’t play soccer if it rains!
マジ?ABCチームに勝ちたいけど、雨じゃ(orではorだったら)、サッカー(を)できないね。 - Leo: Hey, our opponent is ABC, there is no way to win.
ねぇ、相手がABCじゃ(orではorだったら)、勝てないよ。
- Meg: I did nothing but eating and sleeping over the weekend. How about you?
週末は、食べちゃ(orては)寝て、寝ちゃ(orては)食べての繰り返しだった。エイミは? - Amy: My american friend visited me. We went to Akihabara.
アメリカから友達が来て、秋葉原に行った。 - Meg: Great. How long is she staying in Japan?
いいね。いつまで、日本にいるの? - Amy: She went home to the States. Whenever she comes to Tokyo, she goes back home with the latest video games.
もうアメリカに帰ったよ。東京に来ちゃ(orては)、最新のビデオゲームを持って帰るの。
- Meg: Do you know why Kumi took a paid leave today?
なんで今日クミが休んだか知っている? - Amy: Yes, she was dumped by her boyfriend and she seems kind of down. You don’t have to worry about her because Kumi and Jim have been dating on and off for a couple of years.
うん、彼氏に振られて、なんか落ち込んでいるらしい。心配する必要はないけどね。クミとジムは、ここ2,3年付き合っちゃ(orては)別れ、別れちゃ(orては)付き合っているから。 - Meg: I see. Hmm, we’re busy. It’s going to be a problem if she takes a day off tomorrow too.
そうなんだ。んー、忙しい。明日も休みじゃ(orではorだったら)、困るな。