Important: This documentation covers modern versions of Yarn.
For 1.x docs, see classic.yarnpkg.com.
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yarn why

Display the reason why a package is needed.

Usage

$> yarn why <package>

Examples

Explain why lodash is used in your project :

yarn why lodash

Options

Definition
Description

-R,--recursive

List, for each workspace, what are all the paths that lead to the dependency

--json

Format the output as an NDJSON stream

--peers

Also print the peer dependencies that match the specified name

Details

This command prints the exact reasons why a package appears in the dependency tree.

If -R,--recursive is set, the listing will go in depth and will list, for each workspaces, what are all the paths that lead to the dependency. Note that the display is somewhat optimized in that it will not print the package listing twice for a single package, so if you see a leaf named "Foo" when looking for "Bar", it means that "Foo" already got printed higher in the tree.