NPM Configuration

When using npm to install dependencies how does npm install process multiple copies of the .npmrc file if found in multiple levels of a directory hierarchy? For example, if we assume a project directory in ~/projects/app where there is a .npmrc in the app subdirectory, another one in the projects subdirectory and one in the user home directory ~?

When npm installs dependencies, it looks for configuration settings in the .npmrc files within the project directory and its parent directories. The configuration settings are hierarchical, meaning that settings in closer .npmrc files take precedence over those in higher-level directories.

In our example:

1. If there is a .npmrc file in the ~/projects/app directory, npm will use the settings specified in that file.

2. If there is also a .npmrc file in the ~/projects directory, npm will use the settings from that file. These settings will override any conflicting settings in the .npmrc file in the ~/projects/app directory.

3. Finally, if there is a .npmrc file in the user's home directory ~, it will be considered. Any conflicting settings from this file will override those from the project-specific .npmrc files.

This hierarchical approach allows you to have different configuration settings for different projects or directories. Settings in lower-level directories take precedence over settings in higher-level directories.

Keep in mind that npm looks for .npmrc files in the directory where the npm command is run (typically the subdirectory where package.json is located) and its parent directories up to the user's home directory. If multiple .npmrc files are found at different levels, npm combines their settings based on this hierarchy.

To clarify if a given setting is found in all three .npmrc files will the app level setting take precedence?

In the hierarchy of .npmrc files, if a setting is defined in all three .npmrc files (app, projects, and user's home directory), the setting in the .npmrc file at the lowest level (in this case, the one in the ~/projects/app directory) will take precedence. The settings in higher-level .npmrc files will be overridden by conflicting settings in the lower-level ones.

So, if a setting is specified in the .npmrc file within the ~/projects/app directory, it will take precedence over the same setting in the .npmrc files in the ~/projects directory and the user's home directory ~.