Helper for creating cancellable promise-returning functions.
npm install cancellableHelper for creating cancellable promise-returning functions.
 
Example:
``js
import cancellable from 'cancellable'
const promise = cancellable((cancellation, cancelled) => new Promise((resolve, reject) => {
const xhr = new XMLHttpRequest()
xhr.open('GET', '/ajax')
xhr.addEventListener('error', () => reject(new Error('Something went wrong')))
xhr.addEventListener('load', () => resolve(xhr.response))
xhr.send()
cancellation.catch((reason) => {
xhr.abort()
reject(reason)
})
}))
// later
promise.cancel()
`
Takes a promise-returning function that will be passed two arguments:
* cancellation: Promise
A promise that will be rejected with a CancellationError if the cancel method was invoked or otherwise resolves to the fulfilled/rejected value of the promise returned by the function.
* cancelled: () => boolean
A function that returns true if the cancel method was invoked or false otherwise. This function will return true even if the cancel method was invoked after the promise was fulfilled/rejected normally.
Returns the promise returned by the function but adds a cancel method that takes an optional argument:
* message: string
A message that will be used to create a CancellationError. Rejects the promise if it hasn't already been fulfilled/rejected.
A subclass of Error that is used to reject cancelled promises.
As of 1.1.0 it also has a cancelled property (set to true`) to easily distinguish it from other errors.
The MIT/Expat license. For more information, see http://foss-haas.mit-license.org/ or the accompanying LICENSE file.