Check and report duplicate -> [email protected] dependencies -> [email protected] inside your installed npm modules
npm -g i npm-prestige or
yarn global add npm-prestige
npm-prestige
When building large js applications, you sometimes end up with large trees of dependencies. When different dependencies depend on different versions of the same package your final program/bundle will end up with both versions inside. Depending on your application, these extra packages may have negative performance implications (for example if you're developing js for a web application, it will increase the final bundle size the user needs to download over the wire).
Sometimes it gets worse, as npm and yarn won't always dedupe all versions of a package with the same version (if there's another version of the package already installed higher up in the dependency tree) This can lead to the exact same version of a package installed many many times. Note that browserify and some other tools match and dedupe based on the code signature for different dependencies and don't have this problem
Updating your dependencies to all use the same semver range of packages can reduce the final bundle size of your packages.
npm-prestige reports all duplicate dependencies that it finds installed. It uses npm ls under the hood, and only reports un-deduped packages.
Since npm-prestige uses npm under the hood, it has a hidden dependency on the version of npm you've globally installed.
It works fine with all versions of npm that I've tested (4.1.0 and up), but prints nicer output with >4.6.0.
Please submit an issue if it doesn't work with a specific version of npm