isPromise()

isPromise<T>(value): value is Promise<T>

Checks if a value is a Promise or Promise-like object (thenable).

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Type Parameters

T: T = any

The type of the value the promise resolves to.

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Parameters

value: unknown

The value to check.

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Returns: value is Promise<T>

true if the value is a Promise or thenable, false otherwise.

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Since

2.0.0

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Example

isPromise(new Promise(() => {})); // => true
isPromise({ then: () => {} });    // => true
isPromise(async () => {});        // => false (it's a function that returns a promise)
isPromise({});                    // => false

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How it works?

Type guard that checks if a value is a Promise.

Type Narrowing

Common Checks

Value	Result
Promise.resolve(1)	true
new Promise(() => {})	true
async () => {}	false (function)
(async () => {})()	true (called)
{ then: () => {} }	false (thenable)

Note

This checks for native Promise instances. Thenables (objects with .then()) are not detected.

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Use Cases

Detect async operations 📌

Check if a value behaves like a Promise (thenable). Essential for handling mixed synchronous and asynchronous APIs.

#detect#async#Promise#thenable#operations#await

if (isPromise(result)) {
  await result;
}