@byungi/p-cancel NPM

@byungi/p-cancel

A cancelable promise.

Example

import PCancel, {CancelError} from '@byungi/p-cancel'

const requestPromise = new PCancel((resolve, reject, onCancel) => {
    var xhr = new XMLHttpRequest();
    xhr.on('load', resolve);
    xhr.on('error', reject);
    xhr.open('GET', 'http://delay/500ms/call', true);
    xhr.send(null);

    onCancel(()=> xhr.abort())
})

console.log(requestPromise.isCanceled) // => false

setTimeout(()=> {
    requestPromise.cancel() // => After 100ms, xhr is aborted.
}, 100)

requestPromise.catch(err => {
    console.log(err.isCanceled) // => true
    console.log(err instanceof CancelError) // => true
    console.log(requestPromise.isCanceled) // => true
})

API

new PCancel(executor)

PCancel is a promise implementation. Same as promise creation except for onCancel. onCancel receives a function to operate on cancel().

const promise = new PCancel((resolve, reject, onCancel) => {
    const timerId = setTimeout(lazyJob, 1000)
    onCancel(()=> clearTimeout(timerId))
})

promise.cancel(reason)

Execute the cancel operation added with onCancel and throw a CancelError.

promise.isCanceled

Returns whether the promise is canceled.

promise.pipe(onFulfilled, onRejected)

Similar to then but can propagate cancel to the upper promise.

const handleWithRequestPromise = requestPromise.pipe(response => {
    handleResponse(response)
})

handleWithRequestPromise.cancel() // => xhr is aborted