Most of the guides I’ve found on how to do this are fairly involved, requiring you to build from source and install without a .dpkg, which is messy if you ever want to change your installation. Installing Node.js is the same as for Debian:
curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -
sudo apt install -y nodejs
The package build-essential is required for compiling and installing native packages, but it’s already included in Kali’s base image.