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https://github.com/sindresorhus/p-retry
Retry a promise-returning or async function
https://github.com/sindresorhus/p-retry
Last synced: 5 days ago
JSON representation
Retry a promise-returning or async function
- Host: GitHub
- URL: https://github.com/sindresorhus/p-retry
- Owner: sindresorhus
- License: mit
- Created: 2016-10-21T07:44:29.000Z (about 8 years ago)
- Default Branch: main
- Last Pushed: 2024-10-12T06:32:12.000Z (2 months ago)
- Last Synced: 2024-10-29T15:11:27.382Z (about 2 months ago)
- Language: JavaScript
- Size: 52.7 KB
- Stars: 792
- Watchers: 8
- Forks: 63
- Open Issues: 14
-
Metadata Files:
- Readme: readme.md
- License: license
- Security: .github/security.md
Awesome Lists containing this project
- awesome - sindresorhus/p-retry - Retry a promise-returning or async function (JavaScript)
- promise-fun - p-retry - returning or async function (Packages)
README
# p-retry
> Retry a promise-returning or async function
It does exponential backoff and supports custom retry strategies for failed operations.
## Install
```sh
npm install p-retry
```
## Usage
```js
import pRetry, {AbortError} from 'p-retry';
import fetch from 'node-fetch';
const run = async () => {
const response = await fetch('https://sindresorhus.com/unicorn');
// Abort retrying if the resource doesn't exist
if (response.status === 404) {
throw new AbortError(response.statusText);
}
return response.blob();
};
console.log(await pRetry(run, {retries: 5}));
```
## API
### pRetry(input, options?)
Returns a `Promise` that is fulfilled when calling `input` returns a fulfilled promise. If calling `input` returns a rejected promise, `input` is called again until the maximum number of retries is reached. It then rejects with the last rejection reason.
It does not retry on most `TypeError`'s, with the exception of network errors. This is done on a best case basis as different browsers have different [messages](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#Checking_that_the_fetch_was_successful) to indicate this. See [whatwg/fetch#526 (comment)](https://github.com/whatwg/fetch/issues/526#issuecomment-554604080)
#### input
Type: `Function`
Receives the current attempt number as the first argument and is expected to return a `Promise` or any value.
#### options
Type: `object`
Options are passed to the [`retry`](https://github.com/tim-kos/node-retry#retryoperationoptions) module.
##### onFailedAttempt(error)
Type: `Function`
Callback invoked on each retry. Receives the error thrown by `input` as the first argument with properties `attemptNumber` and `retriesLeft` which indicate the current attempt number and the number of attempts left, respectively.
```js
import pRetry from 'p-retry';
const run = async () => {
const response = await fetch('https://sindresorhus.com/unicorn');
if (!response.ok) {
throw new Error(response.statusText);
}
return response.json();
};
const result = await pRetry(run, {
onFailedAttempt: error => {
console.log(`Attempt ${error.attemptNumber} failed. There are ${error.retriesLeft} retries left.`);
// 1st request => Attempt 1 failed. There are 4 retries left.
// 2nd request => Attempt 2 failed. There are 3 retries left.
// …
},
retries: 5
});
console.log(result);
```
The `onFailedAttempt` function can return a promise. For example, you can do some async logging:
```js
import pRetry from 'p-retry';
import logger from './some-logger';
const run = async () => { … };
const result = await pRetry(run, {
onFailedAttempt: async error => {
await logger.log(error);
}
});
```
If the `onFailedAttempt` function throws, all retries will be aborted and the original promise will reject with the thrown error.
##### shouldRetry(error)
Type: `Function`
Decide if a retry should occur based on the error. Returning true triggers a retry, false aborts with the error.
It is not called for `TypeError` (except network errors) and `AbortError`.
```js
import pRetry from 'p-retry';
const run = async () => { … };
const result = await pRetry(run, {
shouldRetry: error => !(error instanceof CustomError);
});
```
In the example above, the operation will be retried unless the error is an instance of `CustomError`.
##### signal
Type: [`AbortSignal`](https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal)
You can abort retrying using [`AbortController`](https://developer.mozilla.org/en-US/docs/Web/API/AbortController).
```js
import pRetry from 'p-retry';
const run = async () => { … };
const controller = new AbortController();
cancelButton.addEventListener('click', () => {
controller.abort(new Error('User clicked cancel button'));
});
try {
await pRetry(run, {signal: controller.signal});
} catch (error) {
console.log(error.message);
//=> 'User clicked cancel button'
}
```
### AbortError(message)
### AbortError(error)
Abort retrying and reject the promise.
### message
Type: `string`
An error message.
### error
Type: `Error`
A custom error.
## Tip
You can pass arguments to the function being retried by wrapping it in an inline arrow function:
```js
import pRetry from 'p-retry';
const run = async emoji => {
// …
};
// Without arguments
await pRetry(run, {retries: 5});
// With arguments
await pRetry(() => run('🦄'), {retries: 5});
```
## Related
- [p-timeout](https://github.com/sindresorhus/p-timeout) - Timeout a promise after a specified amount of time
- [More…](https://github.com/sindresorhus/promise-fun)