Parameter naming: filename or fileName?

Question

I try to be grammatically correct in my naming*. I\'ve always used filename instead of fileName. The java convention also seems to use this, but

Answer 1

Filename ~ an identifying name given to an electronically stored computer file, conforming to limitations imposed by the operating system, as in length or restricted choice of characters.

In the past this was considered two words but now is defined as one word so

var filename = ......

if it was two words it would be

var fileName = ....