Node.js + Express: app won't start listening on port 80

Question

I create and launch an app like this:

express -s -t ejs
npm install express
npm install ejs
node app.js

and it works (on port 3000). But wh

Answer 1

Perhaps there is something else running on port 80 previously?

Perhaps do a port scan and confirm that it is not being used already?

nc -z <> 80