promise

createQueryable

Signature

promise.createQueryable (promiseOrExecutor)

Description

Wraps a Promise or an executor function to make its state synchronously inspectable. By default, JavaScript promises expose no way to know their current state — this function adds isPending(), isFulfilled(), isRejected(), and getStatus() methods to the returned promise.

If the promise passed in is already queryable, it is returned as-is.

Parameters

Name	Type	Required	Description
promiseOrExecutor	Promise | function	yes	A promise or an executor function (resolve, reject) => void

Returns

Type	Description
Promise	The original promise, augmented with state inspection methods

Method	Returns	Description
isPending()	boolean	true if the promise has not yet settled
isFulfilled()	boolean	true if the promise resolved successfully
isRejected()	boolean	true if the promise was rejected
getStatus()	string	One of 'pending', 'fulfilled', 'rejected'

Throws

Throws a TypeError if promiseOrExecutor is neither a Promise nor a function.

Examples

const p = promise.createQueryable(fetch('/api/data'))

p.isPending()   // true
p.isFulfilled() // false
p.isRejected()  // false
p.getStatus()   // 'pending'

await p

p.isPending()   // false
p.isFulfilled() // true
p.isRejected()  // false
p.getStatus()   // 'fulfilled'

// Also accepts an executor function
const p = promise.createQueryable((resolve, reject) => {
  setTimeout(() => resolve(42), 1000)
})

p.isPending() // true
p.getStatus() // 'pending'

// Returns the same instance if already queryable
const p1 = promise.createQueryable(Promise.resolve(42))
const p2 = promise.createQueryable(p1)
p1 === p2 // true