How to install Node.js 10 or 12 on Linux Ubuntu 18.04 / Debian 9 (Stretch) without weird script of the website

EDIT : just follow these instructions from https://github.com/nodesource/distributions/blob/master/README.md#deb :

# Using Ubuntu
curl -sL https://deb.nodesource.com/setup_12.x | sudo -E bash -
sudo apt-get install -y nodejs

# Using Debian, as root
curl -sL https://deb.nodesource.com/setup_12.x | bash -
apt-get install -y nodejs

Because the repository of Node.js is in HTTPS, it is necessary to install this:

sudo apt install apt-transport-https

I add this in /etc/apt/sources.list:

deb https://deb.nodesource.com/node_10.x stretch main

And I do:

wget -q -O - https://deb.nodesource.com/gpgkey/nodesource.gpg.key | sudo apt-key add -
sudo apt update
sudo apt install nodejs

And nothing else!

Notes

Node.js 10 is not compatible on 32 bit system.