Scan it for malware on virus total?
However if you have no need for it, just don't use it.

Well it can basically have all sorts of dangers in there if you execute it AFAIK, so I would suggest you stay away from it.

it can do a lot more harm than you'd think. run random javascript files that you found on the internet and next thing you know your PC have a ransomware. .js malwares is just getting as common as .exe malwares.

Can you open it in an online text editor and add it to his tread in "code" statements.
Also, it is probably a virus, test it if unsure on vrustotal.com
If it is nothing clear when opened in plain text format, it has proably been converted to a binary executable that can load straight from the file and cause problems to the computer, if downloaded, remove immediatly and quarenteen any surrounding files in offline partitions.

Can you post the headers of the email, it can be traced back to originating IP
Take your email out of course by editing and replacing with a made up address.

1.To begin, open the email message by clicking on it.
2.Click on Details (right above the To: and From: fields) and choose View Message Source.
3.The full headers will appear in a new window, simply right-click inside the headers and choose Select All, then right-click again and choose Copy.

Paste the detail here http://www.ip2location.com/free/email-tracer you will then find what country and IP

becareful dude,
step 1 : go to ttps://www.virustotal.com and select tab file.
step 2 : and browser your "bitcoin.js" file
step 3 : Hit "SCAN IT" wait the process
step $ : see the result, if virus total detect some virus, definitely dont open that file!

just advice, do not open any files from strangers. thanks, have a nice day

bitcoin is only a small amount(well under 0.1%) of the world usage..
so its still not something that regular people would recognise, and most scammers still prefer the bank/paypal data grabs for the general public

so chances are someone who knows you and knows that you are interested in bitcoin and knows your drop box might be involved in sending it to you.

i do not think its random or spam otherwise all/many drop box users will be complaining about a bitcoin.js appearing.. so i beleive its more of a specific attack on yourself.

so think hard and long about people you communicate to on the internet and in real life that know about your drop box and also know your interested in bitcoin

It's definitely a virus. I got a similar email today that had "electrum.exe" and "wallet.js"

I also got a share at Dropbox from a user "Poloniex Inc", it was 2 windows executables with some ransomware.