Function: isPromise()

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

Type guard to check if a value is a Promise-like object (thenable). Checks for the presence of 'then' and 'catch' methods.

Type Parameters

T

T = unknown

The type that the Promise resolves to

Parameters

val

unknown

The value to check

Returns

val is Promise<T>

True if the value has Promise-like behavior

Example

const asyncFn = async () => 'result'
const promise = Promise.resolve('value')
const thenable = { then: () => {}, catch: () => {} }

if (isPromise(promise)) {
  // TypeScript knows this is a Promise
  promise.then(value => console.log(value))
}