This Stack Overflow page comes up in Google search results when trying to solve the issue of installing local modules (ie. npm install ../myPackage) and not wanting symbolic links. So I'm adding this answer below to help others who end up here.
Solution #1 - For development environment.
Using the solution proposed by the NPM support team as mentioned in the other answer works...
# Reproduces the old behavior of hard copies and not symlinks
npm install $(npm pack <folder> | tail -1)
This is fine in the development environment for manual installs.
Solution #2 - For build environment.
However, in our case, the development environment doesn't quite matter as much though because when committing our changes to Git, the ./node_modules/ folder is ignored anyway.
The files ./package.json and ./package-lock.json is what is important and is carried into our build environment.
In our build environment (part of our automated CI/CD pipeline), the automation just runs the npm install command and builds from the dependencies listed in the package.json file.
So, here is where the problem affects us. The locally referenced files in the dependencies list of the package.json causes symlinks to appear. Now we are back to the old problem. These symlinks then get carried into the build's output which move onto the Stage and Production environments.
What we did instead is use rsync in archive mode with the --copy-links option that turns symbolic links into copies of the original.
Here is what the command looks like in the automated build:
# Install dependencies based on ./package.json
npm install
# Make a copy that changes symlinks to hard copies
rsync --archive --verbose --copy-links ./node_modules/ ./node_modules_cp/
# Remove and replace
rm -r ./node_modules/
mv ./node_modules_cp/ ./node_modules/
