working-with-a-local-npm-dep.md

Working with a local npm dependency

At times, in your development process, you may have an npm package bar has a dependency on another npm package foo, that you also develop.

In such cases, you want a quick feedback loop. Make changes in foo, build, try out the changes in bar.

Here follows a solution to do exactly that with npm v5 and newer (actually v5.7.1 and newer due to a bug).

If you do have an older npm version, you can upgrade your global npm via npm i -g npm.

Start working with the local dependency

cd path/to/bar
cat package.json | grep foo # shows smth like <"foo": "1.0.0">
npm i path/to/local/foo

NOTE don't worry if foo is a dependency or a dev dependency. npm i works it out on its own.

Explanation

cd path/to/bar
ls -l node_modules | grep foo # shows a symlink <node_modules/foo -> path/to/local/foo>
git status                    # shows that package.json has changed
cat package.json | grep foo   # shows smth like <"foo": "file:path/to/local/repo"

NOTE while obvious for many, this change in package.json should never be committed.

NOTE having a dirty package.json is very nice for two reasons: you don't have to worry that npm i would somehow revert your changes, and you also have a glarying git modification that tell you that you should undo the local-development setup.

stop working with the local dependency

cd path/to/bar
git checkout package.json
cat package.json | grep foo   # shows smth like <"foo": "1.0.0">
make                          # or npm i, etc will remove the symlink and unzip a regular package
ls -l node_modules | grep foo # shows a regular folder <node_modules/foo>