Is Startup Screen flash nw.js a Virus???

I got a few clues.

You are running the chromium web browser. .js is the javascript extension.

I'd say that you didn't quit chromium before you shutdown your machine. Chromium started again when you booted your machine. Chromium reload all the web page the nw.js was on one of these pages.

What to do? I'm not that familiar with Chromium so I'm not sure how you clean out Chromium.

I'd be sure to quit chromium before shutting down. See if the problem goes away.

You could clean out the chromium caches.

These web browser problems tend not to be that serious. They may make your web browsing experience annoying, but rarely effect your machine outside the web browser.

R

Try running this program in your normal account, then copy and paste the output in a reply. The program was created by etresoft, a frequent contributor. Please use copy and paste as screen shots can be hard to read. On the screen with Options, please open Options and check the bottom 2 boxes before running. Click “Share Report” button in the toolbar, select “Copy Report” and then paste into a reply. This will show what is running on your computer. No personal information is shown.

Etrecheck – System Information

you could run malwarebytes. This is the only anti-malware software recommended around here.

https://www.malwarebytes.com/mac/

I seem to recall it is best to run from an administrator account.

R