Typically, the recruiter asks me to do a simple challenge in e.g. a google doc. I'm then strongly pressured to do it in one of their preferred languages, or if

Typically, the recruiter asks me to do a simple challenge in e.g. a google doc. I'm then strongly pressured to do it in one of their preferred languages, or if I do it in Ruby, I have to explain all of the syntax and it takes a lot of time and mental focus away from the actual task. For instance, in a recent interview, I couldn't remember the substr() function in Javascript, which Google insisted I do the challenge in. Instead I wound up using the ruby [range] operator and explaining ranges and what that operator meant. To Google's credit and my moderate surprise, I passed that round of the interview. But I have definitely had interviews where the result is a mash of languages that nobody can really understand. Or they let me do it in ruby and I have to explain every line of the syntax (for instance, how ruby does iteration). There have also definitely been times where they flat out told me that they want a specific language and I should contact them again when I've gotten skill in it. Alternately, if languages don't match, they'll focus the interview on a skill that they need for whatever position, but for which I only have limited expertise. Take SQL. I know what indexes are, I can open a console to identify long running queries, but I mostly work with it through an ORM. But if they hear I have some SQL experience they'll decide to grill me on details of how Postgres handles things like logging and persistence and maintaining multiple versions of rows in memory and what are tuples and so on. I'm not a DBA and will do only mediocre in such interviews. I always mix up the different types of joins, because I hardly ever write join queries and usually look it up when I need it. I'm fairly certain they'd have given me Java questions if I knew Java, but the thing I had experience in that the recruiter knew was SQL.