1. Install python-software-properties

sudo apt-get install python-software-properties

2. add repository chris-lea

sudo add-apt-repository ppa:chris-lea/node.js

3. update apt-get

sudo apt-get update

4. install node.js

sudo apt-get install nodejs

express.js installation

1. install express

npm install -g express

2. check npm installation

npm ls

Done!