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Royal Jain for CodeParrot

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Npm vs Yarn

Npm is the default package manager for Node.js. It was the first package manager for JavaScript, it has a large community and comes bundled with Node.js installations. So why was Yarn created and why it gained so much popularity.


Yarn, was created by Facebook as a faster alternative to NPM. Why is it faster?

Concurrent Installation

Yarn installs multiple packages at the same time, whereas older versions of npm would do this sequentially. This concurrency significantly speeds up the installation process.

Efficient Caching

Yarn caches every package it downloads, so it never needs to download it again. This means that once you've installed a package using Yarn, it's available on your machine offline. npm also caches downloaded packages, but Yarn's caching mechanism was more efficient, especially in its early versions.

Flat Dependency Resolution

Dependency Resolution is the process through which a package manager determines which versions of each package should be installed to satisfy the requirements of all the packages in your project. This includes the dependencies of dependencies, and so on.

Npm resolved dependencies in a nested manner. This means that each package would have its own node_modules directory containing its dependencies, and those dependencies would have their own node_modules directories, and so on. This could lead to a deeply nested structure within the node_modules folder of a project.

Issues with Nested Dependency Resolution

One of the main issues with this approach is the potential for duplication. If different packages required different versions of the same dependency, that dependency would be downloaded and stored multiple times, once for each version required. Due to the potential for duplication the installation process could be slower. This approach could consume more disk space because of the duplicated packages across different dependency trees.

Yarn introduced a flat mode (using the --flat flag) that would install only one version of a package if possible, reducing duplication and minimizing disk space usage. This was particularly advantageous when dealing with large numbers of dependencies.


Over time, npm has closed the performance gap. Now, the choice often comes down to personal or team preference, and familiarity with the tool. Many projects that started with npm have continued to use it due to its improvements over time, while others prefer Yarn for its initial advantages in performance and consistency.

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