p-retry
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    5.1.1 • Public • Published

    p-retry

    Retry a promise-returning or async function

    It does exponential backoff and supports custom retry strategies for failed operations.

    Install

    npm install p-retry

    Usage

    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 to indicate this. See whatwg/fetch#526 (comment)

    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 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.

    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:

    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.

    signal

    Type: AbortSignal

    You can abort retrying using AbortController.

    When AbortController.abort(reason) is called, the promise will be rejected with reason if it's an instance of Error, or a DOMException with reason as its message otherwise. If no reason is provided, the promise will reject with a DOMException.

    Requires Node.js 16 or later.

    import pRetry from 'p-retry';
    
    const run = async () => {  };
    const controller = new AbortController();
    
    cancelButton.addEventListener('click', () => {
    	controller.abort('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:

    import pRetry from 'p-retry';
    
    const run = async emoji => {
    	// …
    };
    
    // Without arguments
    await pRetry(run, {retries: 5});
    
    // With arguments
    await pRetry(() => run('🦄'), {retries: 5});

    Related

    Install

    npm i p-retry

    DownloadsWeekly Downloads

    11,911,386

    Version

    5.1.1

    License

    MIT

    Unpacked Size

    12.7 kB

    Total Files

    5

    Last publish

    Collaborators

    • sindresorhus