How do I install a custom version of NPM/NodeJS

If your project requires a specific version of NPM that isn't available as a selectable language version from the dropdown, you can add the following command to the beginning of your build command, replacing the version of NPM as appropriate:

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.1/install.sh | bash
source $HOME/.nvm/nvm.sh
nvm install 16.14.0