Is there anything like a reverse search engine, that let's you enter e.g. some js code and it tells you what language feature has been used? Imagine you see syntax you've never used before and don't know what it's called or what it does but would like to know more about it.

I know exactly what problem youre facing right now
The worst part is if said syntax uses some special characters and search engines can't handle them well

You can try to put it into quotation marks, afaik that makes the word "absolute" for Google.

Otherwise you might try to search for the feature on certain pages (subreddits, stackoverflow) directly.

Or just post it on devrant and pray someone else has seen it before

All the professional companies like Google and Facebook would be ruined if this happens

@Eklavya hm, searching via google might be good enough.
Why would that be a problem?

Forums are exactly for that, humans know better, but Stackoverflow will be annoyed by such questions.

Go to the language documentation and look for it in the list of operators.

@kodumen that would result searching for the needle in the haystack.
Imagine seeing "a?.b" and you don't know what "?." (optional chaining operator) is. How would you be able to find out, without scraping the whole documentation? Some kind of search engine would be required.

@cb219 If the language used has good documentation, it's not that much of a problem. Ctrl+F is usually enough to narrow it down.