← Back to rules

typescript/no-unnecessary-type-parameters Suspicious

💭 This rule requires type information.

💡 A suggestion is available for this rule.

What it does

Disallow type parameters that are declared but not meaningfully used.

Why is this bad?

Unnecessary type parameters make signatures noisier and harder to understand, and they often hide opportunities to simplify APIs.

Examples

Examples of incorrect code for this rule:

function parseYAML<T>(input: string): T {
  return input as any as T;
}

Examples of correct code for this rule:

function parseYAML(input: string): unknown {
  return input;
}

function identity<T>(value: T): T {
  return value;
}

How to use

To enable this rule using the config file or in the CLI, you can use:

Config (.oxlintrc.json)

{
  "options": {
    "typeAware": true
  },
  "rules": {
    "typescript/no-unnecessary-type-parameters": "error"
  }
}

Config (oxlint.config.ts)

import { defineConfig } from "oxlint";

export default defineConfig({
  options: { typeAware: true },
  rules: {
    "typescript/no-unnecessary-type-parameters": "error",
  },
});

CLI

oxlint --type-aware --deny typescript/no-unnecessary-type-parameters

Version

This rule was added in v1.49.0.

References

• Rule Source
• Upstream rule docs
• Rule Source (tsgolint)