I was curious about this, as I work in multiple languages every day. I almost never use Google though except as last resort if other engines can't find anything. So the result I got for array length was for Javascript. Which is quite high on the hype cycle now, but I only very rarely use it and search anything about it even less frequently.
Sо I wonder how much of the magic you perceive might be just your interests matching the interests of the most other people using Google and thus it's not just Google magically guessing you're into Javascript (for example) now, but Javascript being popular and this being the cause of both Google returning matches for it and you starting to use it? Did you ever do a clean experiment - e.g. try to learn APL or some other relatively obscure language and have Google return all results about APL and none about Javascript?
Sо I wonder how much of the magic you perceive might be just your interests matching the interests of the most other people using Google and thus it's not just Google magically guessing you're into Javascript (for example) now, but Javascript being popular and this being the cause of both Google returning matches for it and you starting to use it? Did you ever do a clean experiment - e.g. try to learn APL or some other relatively obscure language and have Google return all results about APL and none about Javascript?