[jasonkostempski]

I wouldn't call it "hidden". If someone expected that to work, or couldn't figure out what the article example was doing, they just haven't read the documentation for 2 common functions. In fact, last I checked, always using the second parameter of parseInt was considered good practice.

[hdhzy]

There are generally two schools of thought: one is that the programmer should know better, memorize the documention and specs. The other one is that if it violates the principle of least astonishment it's just badly designed. Personally I believe that the truth is somewhere in the middle. It's good to know one's tools (including docs and specs) but I wouldn't call this kind of "clever" code maintainable.