eslint/rules/dead-code

Dead code: Unused, unreachable, useless, empty or duplicated code. Rules of ESLint, typescript-eslint and SonarJS (the Sonar way profile of SonarQube) on this subject, every rule listed; the TypeScript rules apply to TypeScript files only.

16 rules, 13 on. Source: lint/eslint/rules/dead-code.mjs.

Rule	Setting	Files	What it checks	Why
no-debugger	error	JS + TS	Disallow the use of debugger	—
no-empty-pattern	error	JS + TS	Disallow empty destructuring patterns	—
no-self-assign	error	JS + TS	Disallow assignments where both sides are exactly the same	—
no-unreachable	error	JS + TS	Disallow unreachable code after return, throw, continue, and break statements	Kept: TypeScript only greys out dead code, allowUnreachableCode: false would also block the dev loop.
no-useless-assignment	error	JS + TS	Disallow variable assignments when the value is not used	—
no-empty	warn	JS + TS	Disallow empty block statements	—
no-lone-blocks	info	JS + TS	Disallow unnecessary nested blocks	—
no-unused-expressions	error	JS + TS	Disallow unused expressions	Replaced by the TS version.
sonarjs/no-dead-store	off	JS + TS	Unused assignments should be removed	Off: duplicate of no-useless-assignment.
sonarjs/no-duplicate-in-composite	off	JS + TS	Union and intersection types should not include duplicated constituents	Off: duplicate of @typescript-eslint/no-duplicate-type-constituents.
sonarjs/no-redundant-jump	warn	JS + TS	Jump statements should not be redundant	Sonar way; replaces the core no-useless-return, like SonarQube.
sonarjs/no-redundant-optional	warn	JS + TS	Optional property declarations should not use both '?' and 'undefined' syntax	—
no-unreachable	error	TS	Disallow unreachable code after return, throw, continue, and break statements	Kept: TypeScript only greys out dead code, allowUnreachableCode: false would also block the dev loop.
@typescript-eslint/no-unnecessary-qualifier	error	TS	Disallow unnecessary namespace qualifiers	—
no-unused-expressions	off	TS	Disallow unused expressions	Replaced by the TS version.
@typescript-eslint/no-unused-expressions	error	TS	Disallow unused expressions	—