Q:

Is chat abbreviation allowed in answer?

I used some chat abbreviations in my answers and found that someone tried to remove them like this: https://stackoverflow.com/posts/42887142/revisions
So I want to know if it's allowed here.
I did some search with google about this question, but found nothing. 

A:

"Txt spk" is frowned upon, and should be edited out. We're a site for professionals (and enthusiast amateurs). "U" and other forms of "txt spk" are not professional.
So, please use proper English in your posts. And if you see someone use "txt spk" or "l33t spk", by all means convert it to proper English!
The only thing we don't do is changing American English to British English, or vice versa. Both are considered proper English, and merely a matter of the OP's taste.

A:

People don't use here text-speak chat abbreviation in posts, because SO is not a social networking platform, some people may not get the context and might downvote your Q&A.
Quote from Writing the perfect question

Please write actual words. There are undoubtedly some abbreviations
  which are acceptable to most readers – IMO, IIRC etc –  there’s no
  reason to switch into text-speak with “gr8”, “bcoz”, “u” and so forth.
  It’s unlikely that you’re actually writing your question on a phone
  with only a primitive keyboard; show your readers respect by writing
  properly. It may take you a few more seconds, but if it means you get
  an answer quicker, it’s surely worth the extra effort.

and from Help

Spelling, grammar and punctuation are important! Remember, this is the
  first part of your question others will see - you want to make a good
  impression. If you're not comfortable writing in English, ask a friend
  to proof-read it for you.

