no-duplicate-enum-values

Disallow duplicate enum member values.

🔒

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

Although TypeScript supports duplicate enum member values, people usually expect members to have unique values within the same enum. Duplicate values can lead to bugs that are hard to track down.

.eslintrc.cjs

module.exports = {
  "rules": {
    "@typescript-eslint/no-duplicate-enum-values": "error"
  }
};

Try this rule in the playground ↗

Examples

This rule disallows defining an enum with multiple members initialized to the same value.

This rule only enforces on enum members initialized with string or number literals. Members without an initializer or initialized with an expression are not checked by this rule.

❌ Incorrect

enum E {
  A = 0,
  B = 0,
}

enum E {
  A = 'A',
  B = 'A',
}

✅ Correct

enum E {
  A = 0,
  B = 1,
}

enum E {
  A = 'A',
  B = 'B',
}

Options

This rule is not configurable.

Resources

• Rule source
• Test source