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consistent-type-definitions

Enforce type definitions to consistently use either interface or type.

There are two ways to define a type.

// type alias
type T1 = {
  a: string;
  b: number;
};

// interface keyword
interface T2 {
  a: string;
  b: number;
}

Attributes

  • Included in configs
    • ✅ Recommended
    • 🔒 Strict
  • Fixable
    • 🔧 Automated Fixer
    • 💡 Suggestion Fixer
  • 💭 Requires type information
.eslintrc.cjs
module.exports = {
  "rules": {
    "@typescript-eslint/consistent-type-definitions": "warn"
  }
};

Options​

This rule accepts an options string of the following possible values:

type Options = "interface" | "type";

const defaultOptions: Options = ["interface"];
  • "interface" (default): enforce using interfaces for object type definitions.
  • "type": enforce using types for object type definitions.

interface​

/* eslint @typescript-eslint/consistent-type-definitions: ["error", "interface"] */

type T = { x: number };

type​

/* eslint @typescript-eslint/consistent-type-definitions: ["error", "type"] */

interface T {
  x: number;
}

When Not To Use It​

If you specifically want to use an interface or type literal for stylistic reasons, you can disable this rule.

Resources​