The best way to install Node.js on Mac is nvm.
You can use the install script for nvm installation.
$ curl -o- | bash
relaunch your Terminals and check nvm version
$ nvm --version

List your installed node versions if any:
$ nvm list

It is safe if you choose one of the most recent LTS (long time support) version and install it with the following command:
$ nvm install <node-version>

Setup this version as the default.
$ nvm use <node-version>

Check your node version with
$ node -v

In case, you want to upgrade node
$ nvm install <node-version> --reinstall-packages-from=<old-node-version>

To Uninstall Node
$ nvm uninstall <node-version>

Switching between various nodes versions
$ nvm use <node-version> $ nvm use node (switch to latest Node.js version)


npm is installed as a package with Node
Check the version
$ npm -v

To upgrade npm
$ npm install -g npm


To install yarn
$ npm install -g yarn

Check the version
$ yarn -v