JavaScript - Example of regex match

I have the following regex

var reg = /[]\//;

I am trying to figure out what is the example string which can be matchid with this regex. Basically, is there a string str such that reg.test(str); returns true?

Basically, I tried to find on the internet what does empty character set stands for. It says that it matches null. What does it exactly mean? It obviously doesn't match any character nor null character. I tried a lot of example string, but none of these matches.

Can someone explain what does this regex stands for. If it doesn't match any string at all, why the anyone would use empty character set?

P.S. I am talking about JavaScript regex here.