no-unnecessary-type-arguments

Disallow type arguments that are equal to the default.

Warns if an explicitly specified type argument is the default for that type parameter.

Attributes

• Included in configs
  • ✅ Recommended
  • 🔒 Strict
• Fixable
  • 🔧 Automated Fixer
  • 🛠 Suggestion Fixer
• 💭 Requires type information

Rule Details

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.

Examples of code for this rule:

❌ Incorrect

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

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

class C<T = number> {}
function h(c: C<number>) {}
new C<number>();
class D extends C<number> {}

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

✅ Correct

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

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

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

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

Options

// .eslintrc.json
{
  "rules": {
    "@typescript-eslint/no-unnecessary-type-arguments": "warn"
  }
}

This rule is not configurable.