what is node js used for code example

Example 1: what is node.js

Javascript was always a client side language until node.js.
Common server side languages include PHP, Python, Perl, Ruby
and several more. Node enables you to use Javascript server side.
This now means you can have a consistent language both ends
which could not be done prior to Node.

Example 2: node.js

When you install Node.js, you can do these things:
Make web servers
Run JavaScript without an HTML file
...and more!