global variables by default unless you use var every single time
Fail! That's not entirely true for reasons that are obvious if you understand the language. Nice repeated meme though.
Or just use a bigint library, like users of other languages have done for years.
Is there one bigint library on which programmers have standardized, or will three different libraries that I include each bring in their own separate bigint library dependency?
Try learning the language first.
Once I do start to learn the language, how should I go about determining whether the extent to which I have learned the language is enough to allow me not to make a fool of myself here on Slashdot?