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related-getter-setter-pairs

Enforce that get() types should be assignable to their equivalent set() type.

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Extending "plugin:@typescript-eslint/strict-type-checked" in an ESLint configuration enables this rule.

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This rule requires type information to run.

TypeScript allows defining different types for a get parameter and its corresponding set return. Prior to TypeScript 4.3, the types had to be identical. From TypeScript 4.3 to 5.0, the get type had to be a subtype of the set type. As of TypeScript 5.1, the types may be completely unrelated as long as there is an explicit type annotation.

Defining drastically different types for a get and set pair can be confusing. It means that assigning a property to itself would not work:

// Assumes box.value's get() return is assignable to its set() parameter
box.value = box.value;

This rule reports cases where a get() and set() have the same name, but the get()'s type is not assignable to the set()'s.

eslint.config.mjs
export default tseslint.config({
  rules: {
    "@typescript-eslint/related-getter-setter-pairs": "error"
  }
});

Try this rule in the playground ↗

Examples​

interface Box {
  get value(): string;
  set value(newValue: number);
}
Open in Playground

Options​

This rule is not configurable.

When Not To Use It​

If your project needs to model unusual relationships between data, such as older DOM types, this rule may not be useful for you. You might consider using ESLint disable comments for those specific situations instead of completely disabling this rule.

Further Reading​

Type checked lint rules are more powerful than traditional lint rules, but also require configuring type checked linting.

See Troubleshooting > Linting with Type Information > Performance if you experience performance degradations after enabling type checked rules.

Resources​