no-dead-code

Single command to reports unused exports in JS/TS files.

Supports both ES and CommonJS modules out of the box.

The target audience is developers working on refactoring large codebases. Not for script integration since the output is often inaccurate.

Usage

In a project's root, run:

$ npx no-dead-code

Example output

src/client/util/common.js: Unused exports: colors, CONFIG_NAME
src/client/pages/FeedbackTarget/tabs/Results/QuestionResults/utils.js: Unused exports: countAverage, countStandardDeviation, countMedian

Options

--extensions (-e)

Specify which extensions are included. Usually not needed.

Default: mjs cjs js ts tsx jsx

--ignore (-i)

Specify which paths are ignored.

By default, node_modules, .git, dist, build, migrations are always ignored. Values passed to -i are added to these.

You want to ignore files such as webpack, babel and eslint configs. Do not ignore js/tsconfig.

--no-default-ignore

Turn off the default ignores node_modules, .git, dist, build, migrations.

--no-node-stdlib

Do not resolve node standard lib dependencies. They are hardcoded, see src/index.ts for the list which may be incomprehensive.

Dependencies starting with node: are always resolved.

--no-dev

Do not resolve devDependencies in package.json.

Caveats

no-dead-code is far from complete, and should never be relied on blindly. The goal is to cover most typical coding standards, but it will inevitably output false positives and miss unused some exports.

ES modules

Import and export declarations work pretty well. Dynamic imports are considered to import just everything.

CommonJS

Tracking all require-calls and module.exports assignments is a lot of effort, so only typical use cases are covered.

The following are seen by no-dead-code:

module.exports = foo // sees "default" exported. 

module.exports = { // "foo" and "bar" are seen exported
    foo,
    bar,
}

const foo = require('./foo') // everything imported from './foo'

const {
    foo,
    bar,
} = require('./foo') // "foo" and "bar" imported from './foo'

require('./foo')() // everything imported from './foo'

someFunction(require('./foo')) // everything imported from './foo'

Absolute paths

For absolute paths, the closest parent package.json and js/tsconfig are searched to resolve external dependencies and compilerOptions.baseUrl.

The config files are evaluated. Do not run this in a codebase that you do not trust.

Path aliases

js/tsconfig paths are resolved correctly (I think).

In addition, a _moduleAliases field in package.json is used to resolve path aliases.

Webpack path aliases = wontfix

Todo

• Formatted & colored output
• Deeper usage search