Npm "scripts": "start" run express and open url

As far as I know it's like writing a bash command:

// Windows
"start":"start http://localhost:8081 & node bin/www"

// Mac
"start":"open http://localhost:8081 && node bin/www"

// Linux
"start":"xdg-open http://localhost:8081 && node bin/www"

For cross-platform support use open-cli.

Install it:

npm install --save-dev open-cli

Add it to your scripts:

"start": "open-cli http://localhost:8081 && node bin/www"