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prefer-arrow-function-property

Require arrow-function properties when this is not required.

Targeted pattern scope​

This rule targets object-literal properties implemented with a function expression or method shorthand.

What this rule reports​

This rule reports object property functions that do not declare a this parameter and can be represented as arrow-function properties.

Why this rule exists​

Arrow-function properties make this behavior explicit: they capture lexical this and avoid accidental rebinding through call-site context. For codebases that avoid object-method this semantics, this rule enforces a consistent, low-ambiguity style.

❌ Incorrect​

const handlers = {
 onClick() {
  return "clicked";
 },
 onHover: function () {
  return "hovered";
 },
};

✅ Correct​

const handlers = {
 onClick: () => "clicked",
 onHover: () => "hovered",
 withThis(this: void) {
  return "ok";
 },
};

Behavior and migration notes​

This rule has no options.

When migrating, convert method shorthand and function-expression properties to arrow-function properties where this is not used. If a function intentionally uses method-style this, keep it as a method and annotate this explicitly.

Additional examples​

const formatter = {
 prefix: "#",
 format(this: { prefix: string }, value: number) {
  return `${this.prefix}${value}`;
 },
};
// ✅ valid: explicit `this` parameter is allowed by this rule

const formatter2 = {
 format(value: number) {
  return String(value);
 },
};
// ❌ reported

ESLint flat config example​

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

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: {
   "etc-misc/prefer-arrow-function-property": "error",
  },
 },
];

When not to use it​

Disable this rule if your team intentionally prefers method shorthand for object APIs or relies on method-style this semantics.

Package documentation​

Rule catalog ID: R055

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.