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no-unsafe-unary-minus

Require unary negation to take a number.

✅

Extending "plugin:@typescript-eslint/recommended-type-checked" in an ESLint configuration enables this rule.

💭

This rule requires type information to run.

TypeScript does not prevent you from putting a minus sign before things other than numbers:

const s = 'hello';
const x = -s; // x is NaN

This rule restricts the unary - operator to number | bigint.

.eslintrc.cjs
module.exports = {
  "rules": {
    "@typescript-eslint/no-unsafe-unary-minus": "error"
  }
};

Try this rule in the playground ↗

Examples​

declare const a: string;
-a;

declare const b: {};
-b;
Open in Playground

Options​

This rule is not configurable.

When Not To Use It​

Type checked lint rules are more powerful than traditional lint rules, but also require configuring type checked linting.

See Troubleshooting > Linting with Type Information > Performance if you experience performance degredations after enabling type checked rules.

Resources​