asyncUnnecessaryPromiseWrappers

Reports unnecessary Promise.resolve() or Promise.reject() in async contexts.

✅ This rule is included in the ts logical and logicalStrict presets.

Wrapping a return value in Promise.resolve() in an async function or a promise callback is unnecessary because return values are already wrapped in a Promise. Similarly, returning an error wrapped in Promise.reject() is equivalent to throwing the error. This applies to yield expressions in async generators as well.

async function 
function getValue(): Promise<number>
getValue() {
  return 
var Promise: PromiseConstructor
Represents the completion of an asynchronous operation
Promise.
PromiseConstructor.resolve<number>(value: number): Promise<number> (+2 overloads)
Creates a new resolved promise for the provided value.
@param ― value A promise.
@returns ― A promise whose internal state matches the provided promise.
resolve(42);
}

async function 
function failWithError(): Promise<never>
failWithError() {
  return 
var Promise: PromiseConstructor
Represents the completion of an asynchronous operation
Promise.
PromiseConstructor.reject<never>(reason?: any): Promise<never>
Creates a new rejected promise for the provided reason.
@param ― reason The reason the promise was rejected.
@returns ― A new rejected Promise.
reject(new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error("failed"));
}


const promise: Promise<unknown>
promise.
Promise<unknown>.then<number, never>(onfulfilled?: ((value: unknown) => number | PromiseLike<number>) | null | undefined, onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<number>
Attaches callbacks for the resolution and/or rejection of the Promise.
@param ― onfulfilled The callback to execute when the Promise is resolved.
@param ― onrejected The callback to execute when the Promise is rejected.
@returns ― A Promise for the completion of which ever callback is executed.
then(() => 
var Promise: PromiseConstructor
Represents the completion of an asynchronous operation
Promise.
PromiseConstructor.resolve<number>(value: number): Promise<number> (+2 overloads)
Creates a new resolved promise for the provided value.
@param ― value A promise.
@returns ― A promise whose internal state matches the provided promise.
resolve(42));


const promise: Promise<unknown>
promise.
Promise<unknown>.catch<never>(onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<unknown>
Attaches a callback for only the rejection of the Promise.
@param ― onrejected The callback to execute when the Promise is rejected.
@returns ― A Promise for the completion of the callback.
catch(() => 
var Promise: PromiseConstructor
Represents the completion of an asynchronous operation
Promise.
PromiseConstructor.reject<never>(reason?: any): Promise<never>
Creates a new rejected promise for the provided reason.
@param ― reason The reason the promise was rejected.
@returns ― A new rejected Promise.
reject(new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error("error")));

async function 
function getValue(): Promise<number>
getValue() {
  return 42;
}

async function 
function failWithError(): Promise<void>
failWithError() {
  throw new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error("failed");
}


const promise: Promise<unknown>
promise.
Promise<unknown>.then<number, never>(onfulfilled?: ((value: unknown) => number | PromiseLike<number>) | null | undefined, onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<number>
Attaches callbacks for the resolution and/or rejection of the Promise.
@param ― onfulfilled The callback to execute when the Promise is resolved.
@param ― onrejected The callback to execute when the Promise is rejected.
@returns ― A Promise for the completion of which ever callback is executed.
then(() => 42);


const promise: Promise<unknown>
promise.
Promise<unknown>.catch<never>(onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<unknown>
Attaches a callback for only the rejection of the Promise.
@param ― onrejected The callback to execute when the Promise is rejected.
@returns ― A Promise for the completion of the callback.
catch(() => {
  throw new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error("error");
});

function 
function regularFunction(): Promise<number>
regularFunction() {
  return 
var Promise: PromiseConstructor
Represents the completion of an asynchronous operation
Promise.
PromiseConstructor.resolve<number>(value: number): Promise<number> (+2 overloads)
Creates a new resolved promise for the provided value.
@param ― value A promise.
@returns ― A promise whose internal state matches the provided promise.
resolve(42);
}

Options

This rule is not configurable.

When Not To Use It

If you have a codebase that intentionally uses Promise.resolve() and Promise.reject() for consistency across async and non-async functions, you may want to disable this rule.

Equivalents in Other Linters

ESLint: unicorn/no-useless-promise-resolve-reject
Oxlint: unicorn/no-useless-promise-resolve-reject

Made with ❤️‍🔥 around the world by the Flint team and contributors.

asyncUnnecessaryPromiseWrappers

Examples

Options

When Not To Use It

Further Reading

Equivalents in Other Linters