bun why

Explain why a package is installed

The bun why command explains why a package is installed in your project by showing the dependency chain that led to its installation.

Usage

bun why <package>

Arguments

• •<package>: The name of the package to explain. Supports glob patterns like @org/* or *-lodash.

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

Check why a specific package is installed:

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:

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:

bun why express --top

express@4.18.2
  └─ my-app@1.0.0 (requires ^4.18.2)

Limit the dependency tree depth:

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

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.