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The bun why command explains why a package is installed in your project by showing the dependency chain that led to its installation.
[
](#usage)
Usage
terminal
bun why <package>
[
](#arguments)
Arguments
<package>: The name of the package to explain. Supports glob patterns like@org/*or*-lodash.
[
](#options)
Options
--top: Show only the top-level dependencies instead of the complete dependency tree.--depth <number>: Maximum depth of the dependency tree to display.
[
](#examples)
Examples
Check why a specific package is installed:
terminal
bun why react
react@18.2.0
└─ my-app@1.0.0 (requires ^18.0.0)
Check why all packages with a specific pattern are installed:
terminal
bun why "@types/*"
@types/react@18.2.15
└─ dev my-app@1.0.0 (requires ^18.0.0)
@types/react-dom@18.2.7
└─ dev my-app@1.0.0 (requires ^18.0.0)
Show only top-level dependencies:
terminal
bun why express --top
express@4.18.2
└─ my-app@1.0.0 (requires ^4.18.2)
Limit the dependency tree depth:
terminal
bun why express --depth 2
express@4.18.2
└─ express-pollyfill@1.20.1 (requires ^4.18.2)
└─ body-parser@1.20.1 (requires ^1.20.1)
└─ accepts@1.3.8 (requires ^1.3.8)
└─ (deeper dependencies hidden)
[
](#understanding-the-output)
Understanding the Output
The output shows:
- The package name and version being queried
- The dependency chain that led to its installation
- The type of dependency (dev, peer, optional, or production)
- The version requirement specified in each package’s dependencies
For nested dependencies, the command shows the complete dependency tree by default, with indentation indicating the relationship hierarchy.
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