[![NPM Version][npm-image]][npm-url]
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Poll Until Promise

Wait until the executed promise resolved to a true value,
Execute it every x milliseconds and stop after y milliseconds.

Install

npm install poll-until-promise

Usage

$3

``js
const { waitFor } = require('poll-until-promise');

waitFor(() => fetch('/get-data'), { interval: 100 })
// Tries every 100ms (from the last failure)
.then(value => console.log('Yey', value))
.catch(err => console.error(err));

`

$3


`js
import { waitFor, AbortError } from 'poll-until-promise';

async function waitForDomElement(cssSelector = 'div') {
try {
const element = await waitFor(() => {
const element = window.document.querySelector(cssSelector);
if (!element) throw new Error(failed to find element: ${cssSelector});
return element;
}, { timeout: 60_000 });

return element;
} catch (e) {
console.error('faled to find dom element:', e);
throw e;
}
}

async function retryFetch(path = '/get-data') {
try {
const data = await waitFor(async () => {
const res = await fetch(path);

// Stop immediately if the resource doesn't exist
if (res.status === 404) {
throw new AbortError(res.statusText);
}

return res.json();
}, { timeout: 60_000, interval: 1000 });
} catch (e) {
console.error('faled to fetch:', e);
throw e;
}
}
`




$3


`js
const { waitFor } = require('poll-until-promise');

waitFor(() => {
if (Math.random() >= 0.5) {
throw new Error('try again');
} else {
console.log('all good')
}
})
.then(() => console.log('Yey'))
.catch(err => console.error(err));
`

$3


`js
const { PollUntil } = require('poll-until-promise');

const later = Date.now() + 1000; // 1 seconds into the future

let pollUntilPromise = new PollUntil();
pollUntilPromise
.stopAfter(2 * 1000) // Stop trying after 2 seconds
.tryEvery(100) // Tries every 100ms (from the last failure)
.execute(() => {
return new Promise((resolve, reject) => {
if (+Date.now() >= later) {
return resolve(true); // Some truthy value
}
reject(false);
})
})
.then(value => console.log('Yey', value))
.catch(err => console.error(err));

`




Options


`js
const options = {
interval: 100,
backoffFactor: 1, // Exponential interval increase. Defaults to 1, which means no backoff
backoffMaxInterval: 250, // Sets a maximum interval when using backoff. Defaults to the timeout value
timeout: 1000,
stopOnFailure: false, // Ignores promise rejections
verbose: false,
message: 'Waiting for time to pass :)', // custom message to display on failure
maxAttempts: 5, // maximum attempts to make (default: no limit). Will still fail to wait if reaching timeout before attempts exhausted
};
let pollUntilPromise = new PollUntil(options);
`

Methods

* isResolved
`js
pollUntilPromise.isResolved()
`

* isWaiting
`js
pollUntilPromise.isWaiting()
`

* getPromise
`js
pollUntilPromise.getPromise().then(() => console.log('OMG'))
`

Static Function

`js
const PollUntil = require('poll-until-promise');
const later = Date.now() + 1000; // 1 seconds into the future

let pollUntilPromise = new PollUntil();
pollUntilPromise
.stopAfter(2 * 1000)
.tryEvery(100)
.execute(() => {
if (+Date.now() >= later) {
return true;
}
return false;
})
.then((value) => console.log('Yey', value))
.catch((err) => console.error(err));

``

[npm-url]: https://npmjs.org/package/poll-until-promise
[npm-image]: https://img.shields.io/npm/v/poll-until-promise.svg