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typescript/prefer-class-method

Prefer class methods over untyped arrow-function class properties.

Targeted pattern scope​

This rule targets class property definitions whose value is an arrow function and whose property itself has no explicit type annotation.

What this rule reports​

This rule reports class property arrow functions that have no explicit property type annotation.

Why this rule exists​

Method syntax is often clearer for class behavior and avoids extra per-instance function property declarations.

❌ Incorrect​

class C {
 value = () => {};
}

✅ Correct​

class C {
 value(): void {}
}

Behavior and migration notes​

This rule reports only and does not provide an autofix.

A typed function property (for example x: () => void = () => {}) is not reported by this rule.

Options​

This rule has no options.

Additional examples​

class C {
 handler: () => void = () => {};
}
// ✅ valid (explicit property type annotation)

ESLint flat config example​

import etcMisc from "eslint-plugin-etc-misc";

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: {
   "etc-misc/typescript/prefer-class-method": "error",
  },
 },
];

When not to use it​

Disable this rule if class-property arrow functions are your preferred pattern.

Package documentation​

Rule catalog ID: R131

Further reading​

Adoption resources​

  • Start at warning level in CI, then move to error after cleanup.
  • Use focused codemods/autofix batches per package or directory.