Finding unused and missing npm dependencies with depcheck

Unused dependencies in the project increases installation time, and every time we upgrade depdendencies we spend more time than necessary updating packages we don’t use. Depcheck could identify which of the depdendencies listed in project’s package.json aren’t used and could be removed.

1. Run depcheck in the project root directory:

npx depcheck . --specials=babel,bin,eslint,husky,jest,lint-staged,prettier,webpack

Note The --specials option defines additional dependency checkers, like ESLint or webpack configuration files.

We should see something like this:

Unused devDependencies
* @storybook/addon-a11y
* @storybook/addons
* @types/cypress
* @types/jest
* @types/react-dom
* babel-plugin-transform-async-to-promises
* babel-preset-react-app
* core-js
* jest-environment-jsdom-sixteen
* typescript-styled-plugin
* webpack-cli
Missing dependencies
* eslint-config-airbnb-base: ./.eslintrc.js
* @typescript-eslint/eslint-plugin: ./.eslintrc.js
* eslint-plugin-react: ./.eslintrc.js
* eslint-config-prettier: ./.eslintrc.js
* eslint-plugin-import: ./.eslintrc.js
* history: ./src/pages/BookingManagementPage/BookingManagementPage.stories.tsx

Unfortunately, there are many false positives but some dependencies are actually unused. So we should check each manually before removing anything.