These are most used slangs when texting.
Lol/lmao(laughing out

loud )=笑
Ikr(I know right)=それな
Ttyl(talk to you later)=またあとで話そう
Dope/lit(same as かっこいいbut used when you want to compliment something, not for person)
Example: that jacket is dope
Rn(right now)=なう
Omg(oh my god/gosh)=オーマイがーって感じ？
ily(I love/like you)=愛してる/好き
If you have questions about America or anything I’ll answer