unbound-method.md

Enforces unbound methods are called with their expected scope (unbound-method)

Warns when a method is used outside of a method call.

Class functions don't preserve the class scope when passed as standalone variables.

Rule Details

Examples of incorrect code for this rule

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;

Examples of correct code for this rule

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.log.bind(instance);
const innerLog = () => instance.log();

Options

The rule accepts an options object with the following property:

• ignoreStatic to not check whether static methods are correctly bound

ignoreStatic

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

class OtherClass {
  static log() {
    console.log(OtherClass);
  }
}

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

log();

Example

{
  "@typescript-eslint/unbound-method": [
    "error",
    {
      "ignoreStatic": true
    }
  ]
}

When Not To Use It

If your code intentionally waits to bind methods after use, such as by passing a scope: this along with the method, you can disable this rule.

Related To

• TSLint: no-unbound-method