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What is the difference between dependencies, devDependencies, and peerDependencies?

Q: What is the difference between dependencies, devDependencies, and peerDependencies?

**TL;DR.** dependencies are needed at **runtime** (shipped). devDependencies are needed only for **development/build/test** (not installed in production with --omit=dev ). peerDependencies declare a package your **host app must provide** (e.g. a React plugin expecting react ), avoiding duplicate copies. dependencies runtime shipped to prod devDependencies <text class='d-sub' x='229' y='84' text-ancho

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Distinguish between the different dependency classifications in a package.json file.

npmpackagearchitecture

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Three buckets in a library's manifest

{
  "dependencies":     { "lodash": "^4.17.21" },   // needed at runtime
  "devDependencies":  { "jest": "^29.0.0", "typescript": "^5.4.0" },
  "peerDependencies": { "react": ">=18" }          // host app must provide
}
// prod install skips jest/typescript:  npm ci --omit=dev

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