Why my $SHELL is bash, but .zshrc works instead of .bashrc .bash_profile?

[Rocke]

I found this thread also useful:

Import .bashrc file to .zshrc

I’ ve installed Manjaro 21.1.6 Pahvo and I found it comes with zsh by default which is great, but my issue is next. When I install nvm from its github repository the installation updates my .bashrc but not the .zshrc file, of course, I can copy the exporting part of nvm from .bashrc to zshrc and have it ready, but my question is. How to import all the configurations from .bashrc in the .zshrc file so that I’ll touch it just once? Thanks in advance.