no-unnecessary-type-arguments

Disallow type arguments that are equal to the default.

🔒

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

🔧

Some problems reported by this rule are automatically fixable by the --fix ESLint command line option.

💭

This rule requires type information to run.

Type parameters in TypeScript may specify a default value. For example:

function f<T = number>(...) {...}

It is redundant to provide an explicit type parameter equal to that default: e.g. calling f<number>(...). This rule reports when an explicitly specified type argument is the default for that type parameter.

.eslintrc.cjs

module.exports = {
  "rules": {
    "@typescript-eslint/no-unnecessary-type-arguments": "error"
  }
};

Try this rule in the playground ↗

Examples

❌ Incorrect

function f<T = number>() {}
f<number>();

function g<T = number, U = string>() {}
g<string, string>();

class C<T = number> {}
new C<number>();

class D extends C<number> {}

interface I<T = number> {}
class Impl implements I<number> {}

✅ Correct

function f<T = number>() {}
f();
f<string>();

function g<T = number, U = string>() {}
g<string>();
g<number, number>();

class C<T = number> {}
new C();
new C<string>();

class D extends C {}
class D extends C<string> {}

interface I<T = number> {}
class Impl implements I<string> {}

This rule is not configurable.

Options

Resources

• Rule source
• Test source