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no-constructor-bind

Discourage binding an instance method to this in a class constructor.

Targeted pattern scope​

This rule inspects direct constructor-body assignments where a this property is assigned the result of binding the same this method to the instance.

What this rule reports​

The rule reports direct constructor-body assignments shaped exactly like:

this.handle = this.handle.bind(this);

The assigned and bound property names must be the same, both properties must be non-computed, and this must be the sole bind argument. Nested assignments and bindings of another method are ignored.

Why this rule exists​

Constructor binding adds boilerplate and allocates another function while an instance arrow field can express lexical this directly.

❌ Incorrect​

class Handler {
 constructor() {
  this.handle = this.handle.bind(this);
 }

 handle(): void {}
}

✅ Correct​

class Handler {
 handle = (): void => {};
}
class Handler {
 constructor() {
  this.handle = this.other.bind(this); // different properties: not migrated
 }
}

Behavior and migration notes​

This rule never auto-fixes. It offers a suggestion only for a concrete, non-static, non-generator method without decorators or syntax that depends on method semantics such as super, arguments, yield, or new.target.

Even the suggestion is a semantic migration: prototype methods and instance arrow fields differ in allocation, inheritance, spying, decoration, and property behavior. Review every suggestion.

ESLint flat config example​

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

export default [
 {
  plugins: { "etc-misc": etcMisc },
  rules: { "etc-misc/no-constructor-bind": "warn" },
 },
];

When not to use it​

Disable the rule when bound prototype methods are an intentional API or when class fields are unavailable in the target runtime.

Package documentation​

Rule catalog ID: R028

Further reading​

Upstream inspiration​

Clean-room modernization of eslint-plugin-no-constructor-bind.

Additional resources​

Adoption resources​

  • Start at warning level in CI, then move to error after cleanup.
  • Apply suggestions individually and review the resulting class-field semantics.