no-generated-empty-object-type
Disallow type operations that resolve to the "empty object" type.
Extending "plugin:@typescript-eslint/strict-type-checked" in an ESLint configuration enables this rule.
This rule requires type information to run, which comes with performance tradeoffs.
The {}, or "empty object" type, allows any value except null and undefined.
It is rarely what you want it to be: even primitives such as 0 and "" are assignable to it.
no-empty-object-type reports {} written out by hand.
This rule instead reports type operations that resolve to {}, which is usually a sign that the operation went wrong.
For example, Omit<T, K> distributes over a union, so Omit<null | { a: number; b: string }, 'a'> resolves to {} rather than null | { b: string }.
- Flat Config
- Legacy Config
export default defineConfig({
rules: {
"@typescript-eslint/no-generated-empty-object-type": "error"
}
});
module.exports = {
"rules": {
"@typescript-eslint/no-generated-empty-object-type": "error"
}
};
Try this rule in the playground ↗
Examples
- ❌ Incorrect
- ✅ Correct
type Data = { name: string; value: number };
type NullableData = null | Data;
// `Omit<null>` becomes {}, so this is `{} | { value: number }`, or `{}`
type Unexpected = Omit<NullableData, 'name'>;
type Data = { name: string; value: number };
type NullableData = null | Data;
// This is effectively Omit<Data, 'name'>, which is { value: number }
type Expected = Omit<NonNullable<NullableData>, 'name'>;
Options
This rule is not configurable.
When Not To Use It
If you intentionally rely on type operations producing {}, such as to describe "any non-nullish value" for non-trivial type logic, this rule may not be for you.
Note that NonNullable<unknown> is a more explicit way to write that type, and is still reported by this rule.
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.