---
description: 'Enforce unbound methods are called with their expected scope.'
---

import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';

> 🛑 This file is source code, not the primary documentation location! 🛑
>
> See **https://typescript-eslint.io/rules/unbound-method** for documentation.

Class method functions don't preserve the class scope when passed as standalone variables ("unbound").
If your function does not access `this`, [you can annotate it with `this: void`](https://www.typescriptlang.org/docs/handbook/2/functions.html#declaring-this-in-a-function), or consider using an arrow function instead.
Otherwise, passing class methods around as values can remove type safety by failing to capture `this`.

This rule reports when a class method is referenced in an unbound manner.

:::note Tip
If you're working with `jest`, you can use [`eslint-plugin-jest`'s version of this rule](https://github.com/jest-community/eslint-plugin-jest/blob/main/docs/rules/unbound-method.mdx) to lint your test files, which knows when it's ok to pass an unbound method to `expect` calls.
:::

## Examples

<Tabs>
<TabItem value="❌ Incorrect">

```ts
class MyClass {
  public log(): void {
    console.log(this);
  }
}

const instance = new MyClass();

// This logs the global scope (`window`/`global`), not the class instance
const myLog = instance.log;
myLog();

// This log might later be called with an incorrect scope
const { log } = instance;

// arith.double may refer to `this` internally
const arith = {
  double(x: number): number {
    return x * 2;
  },
};
const { double } = arith;
```

</TabItem>
<TabItem value="✅ Correct">

```ts
class MyClass {
  public logUnbound(): void {
    console.log(this);
  }

  public logBound = () => console.log(this);
}

const instance = new MyClass();

// logBound will always be bound with the correct scope
const { logBound } = instance;
logBound();

// .bind and lambdas will also add a correct scope
const dotBindLog = instance.logBound.bind(instance);
const innerLog = () => instance.logBound();

// arith.double explicitly declares that it does not refer to `this` internally
const arith = {
  double(this: void, x: number): number {
    return x * 2;
  },
};
const { double } = arith;
```

</TabItem>
</Tabs>

## Options

### `ignoreStatic`

Examples of **correct** code for this rule with `{ ignoreStatic: true }`:

```ts option='{ "ignoreStatic": true }' showPlaygroundButton
class OtherClass {
  static log() {
    console.log(OtherClass);
  }
}

// With `ignoreStatic`, statics are assumed to not rely on a particular scope
const { log } = OtherClass;

log();
```

## When Not To Use It

If your project dynamically changes `this` scopes around in a way TypeScript has difficulties modeling, this rule may not be viable to use.
One likely difficult pattern is if your code intentionally waits to bind methods after use, such as by passing a `scope: this` along with the method.
You might consider using [ESLint disable comments](https://eslint.org/docs/latest/use/configure/rules#using-configuration-comments-1) for those specific situations instead of completely disabling this rule.

If you're wanting to use `toBeCalled` and similar matches in `jest` tests, you can disable this rule for your test files in favor of [`eslint-plugin-jest`'s version of this rule](https://github.com/jest-community/eslint-plugin-jest/blob/main/docs/rules/unbound-method.mdx).
