npm error: tunneling socket could not be established, cause=connect ETIMEDOUT

ruby-on-rails heroku command-line terminal npm

Removing the proxy settings resolved the issue:

npm config rm proxy
npm config rm https-proxy

ruby-on-rails heroku command-line terminal npm

npm config set registry=http://registry.npmjs.org/ npm config set strict-ssl false

It's worked for me!

CodeHunter