Installing on macOS with MacPorts

The MacPorts project (http://www.macports.org/) has for years been packaging a long list of open source software packages for macOS, and they have packaged Node.js. After you have installed MacPorts using the installer on their website, installing Node.js is pretty much this simple:

$ port search nodejs npm
...
nodejs6 @6.12.0 (devel, net)
 Evented I/O for V8 JavaScript

nodejs7 @7.10.1 (devel, net)
 Evented I/O for V8 JavaScript

nodejs8 @8.9.1 (devel, net)
 Evented I/O for V8 JavaScript

nodejs9 @9.2.0 (devel, net)
 Evented I/O for V8 JavaScript

Found 6 ports.
--
npm4 @4.6.1 (devel)
 node package manager

npm5 @5.5.1 (devel)
 node package manager

Found 4 ports.

$ sudo port install nodejs8 npm5
.. long log of downloading and installing prerequisites and Node
$ which node
/opt/local/bin/node
$ node --version
v8.9.1