backoff vs async-retry vs promise-retry vs retry vs retry-axios vs retry-request
JavaScript Retry Libraries
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JavaScript Retry Libraries

Retry libraries in JavaScript provide mechanisms to automatically retry failed asynchronous operations, such as API calls or database queries, to enhance reliability and resilience in applications. These libraries help manage transient errors by implementing various retry strategies, allowing developers to configure parameters like the number of retries, delay between attempts, and conditions for retrying. This is particularly useful in scenarios where network issues or temporary service outages may occur, ensuring that applications can gracefully handle failures without crashing or requiring manual intervention.

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Feature Comparison: backoff vs async-retry vs promise-retry vs retry vs retry-axios vs retry-request

Retry Strategy

  • backoff:

    backoff provides built-in support for exponential backoff strategies, allowing you to define the initial delay and the factor by which the delay increases with each retry, making it ideal for handling rate limits.

  • async-retry:

    async-retry allows for custom retry strategies, including exponential backoff and fixed delays. You can specify how long to wait between retries and how many attempts to make before failing.

  • promise-retry:

    promise-retry offers a simple retry strategy that can be customized with a delay function, allowing you to control the timing of retries based on the error type or other conditions.

  • retry:

    retry supports both fixed and exponential backoff strategies, giving you the flexibility to define how retries are handled based on your application's needs.

  • retry-axios:

    retry-axios allows you to configure retry strategies directly in your Axios requests, including setting retry limits and delays, making it easy to manage HTTP request failures.

  • retry-request:

    retry-request provides a straightforward retry mechanism for HTTP requests, allowing you to specify the number of retries and the delay between attempts, suitable for simple use cases.

Integration

  • backoff:

    backoff is a standalone library that can be used with any asynchronous operation, making it versatile for different use cases beyond just HTTP requests.

  • async-retry:

    async-retry is designed to work independently and can be integrated into any promise-based workflow, providing flexibility in various environments.

  • promise-retry:

    promise-retry is specifically tailored for promises, ensuring seamless integration with promise-based APIs and workflows, making it easy to implement in modern JavaScript applications.

  • retry:

    retry can be used with both callbacks and promises, making it a versatile choice for applications that may use either approach for asynchronous operations.

  • retry-axios:

    retry-axios is specifically designed for use with Axios, providing a seamless integration that allows you to add retry logic directly to your HTTP requests without additional setup.

  • retry-request:

    retry-request is built to work with the request library, making it ideal for legacy applications that rely on this library for HTTP requests.

Configuration Options

  • backoff:

    backoff allows for extensive configuration of backoff strategies, including setting maximum retry limits and customizing the backoff function, making it highly adaptable to specific requirements.

  • async-retry:

    async-retry offers a wide range of configuration options, including the ability to customize the number of retries, delay between attempts, and conditions for retrying, providing great flexibility.

  • promise-retry:

    promise-retry provides straightforward configuration options, allowing you to specify the number of retries and a delay function, making it easy to set up and use.

  • retry:

    retry offers flexible configuration options for retry attempts, delays, and error handling, allowing you to tailor the retry logic to fit your needs.

  • retry-axios:

    retry-axios allows you to configure retry options directly in your Axios instance, including retry limits and conditions, making it convenient for developers familiar with Axios.

  • retry-request:

    retry-request provides basic configuration options for retry attempts and delays, making it easy to use without overwhelming complexity.

Error Handling

  • backoff:

    backoff provides mechanisms to handle specific errors and can be configured to retry only on certain error types, making it useful for managing different failure scenarios.

  • async-retry:

    async-retry allows you to specify error types that should trigger a retry, giving you control over which errors are retried and which are not, enhancing error handling capabilities.

  • promise-retry:

    promise-retry allows for custom error handling by enabling you to define conditions under which retries should occur, ensuring that only relevant errors trigger a retry.

  • retry:

    retry provides basic error handling capabilities, allowing you to specify which errors should be retried, but may require additional logic for more complex scenarios.

  • retry-axios:

    retry-axios integrates error handling directly into Axios, allowing you to specify which HTTP status codes should trigger a retry, making it easy to manage API errors.

  • retry-request:

    retry-request allows you to define which HTTP status codes should trigger a retry, providing a straightforward way to handle common HTTP errors.

Documentation and Community Support

  • backoff:

    backoff is well-documented with clear examples, and it has a supportive community that can assist with common use cases and issues.

  • async-retry:

    async-retry has comprehensive documentation and a growing community, making it easy to find examples and support for implementation.

  • promise-retry:

    promise-retry has straightforward documentation that covers the basics, making it easy for developers to get started quickly with examples and use cases.

  • retry:

    retry has decent documentation, but may lack some advanced examples; however, it is widely used, providing a level of community support through forums and GitHub.

  • retry-axios:

    retry-axios has good documentation that integrates with Axios documentation, making it easy for developers familiar with Axios to implement retry logic effectively.

  • retry-request:

    retry-request has basic documentation that covers its usage, but as the request library is deprecated, community support may be limited.

How to Choose: backoff vs async-retry vs promise-retry vs retry vs retry-axios vs retry-request

  • backoff:

    Select backoff if you require advanced exponential backoff strategies with customizable delay and maximum retry limits. It is particularly useful for handling rate-limited APIs or services that enforce throttling.

  • async-retry:

    Choose async-retry if you need a simple and flexible retry mechanism that supports both promises and async/await syntax. It allows for custom backoff strategies and is lightweight, making it suitable for most use cases.

  • promise-retry:

    Opt for promise-retry if you want a straightforward solution specifically designed for promises. It provides built-in support for retrying failed promises with customizable retry conditions and delays, making it easy to integrate into promise-based workflows.

  • retry:

    Use retry if you need a general-purpose retry library that works with both callbacks and promises. It offers a simple API and allows for flexible configuration of retry attempts and delays, suitable for various asynchronous operations.

  • retry-axios:

    Choose retry-axios if you are using Axios for HTTP requests and want to add retry functionality seamlessly. It integrates directly with Axios, allowing you to specify retry logic directly in your Axios configuration, making it ideal for RESTful API interactions.

  • retry-request:

    Select retry-request if you are working with the request library and need a retry mechanism for HTTP requests. It provides a straightforward way to add retry capabilities to your request calls, making it suitable for legacy applications that still use the request library.

Similar Npm Packages to backoff

backoff is a JavaScript library designed to implement exponential backoff strategies for retrying failed asynchronous operations. This is particularly useful in scenarios where you need to handle transient errors, such as network requests or API calls, that may succeed if retried after a certain delay. The backoff library provides a simple and flexible API to configure the retry strategy, including options for maximum retries, delay intervals, and jitter to avoid thundering herd problems.

While backoff is a solid choice for implementing retry logic, there are several alternatives available in the ecosystem that offer similar functionalities. Here are a few noteworthy options:

  • async-retry is a lightweight library that provides a simple way to retry asynchronous functions with customizable retry strategies. It allows you to specify the number of retries, delay intervals, and even a custom retry condition. async-retry is particularly useful for handling promises and can be easily integrated into existing asynchronous workflows, making it a great choice for developers looking for a straightforward retry mechanism.

  • exponential-backoff is a library that focuses specifically on implementing the exponential backoff algorithm. It provides a simple API to configure the backoff strategy, including options for maximum delay and jitter. This library is ideal for developers who want a dedicated solution for exponential backoff without additional features that may come with more comprehensive libraries.

  • promise-retry is another library that allows you to retry promise-returning functions with a customizable retry strategy. It supports both linear and exponential backoff strategies and provides options for maximum retries and delay intervals. promise-retry is a good choice for developers who want a straightforward way to handle retries for promises while maintaining control over the retry logic.

  • retry is a versatile library that provides a simple way to retry any function, including synchronous and asynchronous ones. It offers a variety of options for configuring the retry strategy, including exponential backoff, maximum retries, and delay intervals. retry is suitable for developers looking for a general-purpose retry mechanism that can handle both promise-based and callback-based functions.

To see how backoff compares with async-retry, exponential-backoff, promise-retry, and retry, check out the comparison: Comparing async-retry vs backoff vs exponential-backoff vs promise-retry vs retry.

Similar Npm Packages to async-retry

async-retry is a utility library for retrying asynchronous functions in JavaScript. It provides a simple and flexible way to handle retries for operations that may fail intermittently, such as network requests or database operations. With async-retry, developers can easily specify the number of retries, delay between attempts, and conditions under which to retry, making it a powerful tool for improving the resilience of applications. However, there are several alternatives available that offer similar functionality. Here are a few noteworthy options:

  • p-retry is a promise-based retry utility that allows you to retry asynchronous functions with customizable options. It is designed to work seamlessly with promises, making it a great choice for modern JavaScript applications. p-retry provides a straightforward API for defining retry logic, including the number of retries, delay between attempts, and error handling. If you are looking for a lightweight and promise-centric solution for retrying asynchronous operations, p-retry is an excellent option.

  • promise-retry is another library that focuses on retrying promise-returning functions. It offers a simple API for defining retry logic, including options for maximum retries, delay, and exponential backoff. promise-retry is particularly useful for scenarios where you need to handle transient errors in asynchronous operations, such as API calls or database queries. If you prefer a library that emphasizes simplicity and ease of use, promise-retry is worth considering.

  • retry is a more general-purpose retry utility that can be used with both synchronous and asynchronous functions. It provides a flexible API for configuring retries, including options for maximum attempts, delay, and backoff strategies. retry is suitable for a wide range of use cases, making it a versatile choice for developers who need a robust retry mechanism. If you require a library that can handle both sync and async operations with customizable retry logic, retry is a solid option.

  • retry-axios is a specialized library designed to work with Axios, the popular HTTP client for JavaScript. It provides automatic retry functionality for failed HTTP requests, making it easy to handle transient errors in network communication. With retry-axios, you can configure retry options such as the number of attempts and delay between retries, all while leveraging the familiar Axios API. If you are using Axios for your HTTP requests and want to add retry capabilities, retry-axios is a great choice.

For a comprehensive comparison of these libraries, check out the link: Comparing async-retry vs p-retry vs promise-retry vs retry vs retry-axios.

Similar Npm Packages to promise-retry

promise-retry is a utility library that allows developers to retry asynchronous operations that return promises. This can be particularly useful for handling transient errors in network requests or other operations that may fail intermittently. By providing a simple API to specify the number of retries and the delay between attempts, promise-retry helps ensure that applications can gracefully handle failures and improve their resilience.

While promise-retry is a solid choice for retrying promises, there are several alternatives in the JavaScript ecosystem that offer similar functionality. Here are a few noteworthy options:

  • async-retry is a library designed for retrying asynchronous functions with a simple and flexible API. It allows developers to specify the number of retries, delay between attempts, and even customize the retry logic based on the type of error encountered. async-retry is particularly useful for scenarios where you need more control over the retry behavior and want to handle different types of errors differently.

  • p-retry is another lightweight library that focuses on retrying promises. It provides a straightforward API that allows you to specify the number of retries, delay, and a predicate function to determine if the operation should be retried based on the error. p-retry is a great choice for developers looking for a simple and effective way to implement retry logic in their applications without additional overhead.

  • promise-poller is a utility for polling asynchronous operations until they succeed or a specified timeout is reached. While it is not strictly a retry library, it can be used to repeatedly check the status of an operation at specified intervals. This is especially useful for scenarios where you need to wait for a resource to become available or for a condition to be met.

  • retry is a more general-purpose library for retrying functions, not limited to promises. It provides a flexible way to specify retry strategies, including exponential backoff and custom error handling. This library is suitable for developers who want a more comprehensive solution for retrying both synchronous and asynchronous operations.

  • retry-axios is an Axios interceptor that automatically retries failed HTTP requests. It integrates seamlessly with Axios, allowing developers to specify retry logic directly in their HTTP client configuration. If you are using Axios for making HTTP requests and want built-in retry functionality, retry-axios is an excellent choice.

To see how promise-retry compares with async-retry, p-retry, promise-poller, retry, and retry-axios, check out the comparison: Comparing async-retry vs p-retry vs promise-poller vs promise-retry vs retry vs retry-axios.

Similar Npm Packages to retry

retry is a versatile npm package designed to provide a simple way to retry asynchronous operations in JavaScript. This can be particularly useful in scenarios where network requests or other operations may fail intermittently and need to be retried. The retry package allows developers to specify the number of attempts, delay between attempts, and other customizable options, making it a flexible solution for handling transient errors.

While retry is a solid choice, there are several alternatives in the ecosystem that offer similar functionality with different features and approaches. Here are a few noteworthy alternatives:

  • async-retry is a lightweight library that provides a simple way to retry asynchronous functions with customizable options. It supports exponential backoff and allows you to define the number of attempts and the delay between retries. async-retry is particularly useful for handling promises and works seamlessly with async/await syntax, making it a great choice for modern JavaScript applications.

  • backoff is a library that implements exponential backoff algorithms for retrying operations. It provides a more sophisticated approach to retries, allowing developers to define custom backoff strategies. This can be particularly useful in scenarios where you want to avoid overwhelming a server with repeated requests in a short period. backoff is suitable for applications that require fine-tuned control over retry behavior.

  • promise-retry is another library focused on retrying promise-based functions. It offers a straightforward API for retrying failed promises with customizable options for the number of retries and delay. promise-retry is a good choice for developers who want a simple and effective way to handle retries in promise-based workflows.

  • retry-axios is a specialized library that integrates the retry functionality directly with the Axios HTTP client. It allows you to automatically retry failed HTTP requests made with Axios, providing a seamless experience for handling transient network errors. If you are already using Axios in your application, retry-axios can be a great addition to enhance its resilience.

  • retry-request is a library that extends the functionality of the popular request library by adding retry capabilities. It allows you to specify retry options for HTTP requests, making it easier to handle transient errors when making network calls. If you are using the request library, retry-request can provide a straightforward way to add retry logic to your requests.

To compare these packages and see how they stack up against each other, check out the following link: Comparing async-retry vs backoff vs promise-retry vs retry vs retry-axios vs retry-request.

Similar Npm Packages to retry-axios

retry-axios is a library that enhances the functionality of Axios, a popular HTTP client for JavaScript. It provides a mechanism to automatically retry failed HTTP requests, making it easier to handle transient errors such as network issues or server unavailability. By integrating retry logic directly into Axios, retry-axios allows developers to configure how many times a request should be retried, the delay between retries, and which types of errors should trigger a retry. This can significantly improve the resilience of applications that rely on external APIs.

While retry-axios offers a robust solution for retrying requests, there are several alternatives in the ecosystem that provide similar functionalities:

  • axios-retry is another popular library that adds retry functionality to Axios. It allows developers to specify the number of retries, the delay between retries, and conditions under which a retry should occur. axios-retry is straightforward to use and integrates seamlessly with Axios, making it a solid choice for those looking to add retry logic to their HTTP requests without much overhead.

  • fetch-retry is designed for the Fetch API, providing a similar retry mechanism for requests made using the Fetch API. This library allows developers to specify retry options, such as the number of attempts and the delay between retries. If your application uses the Fetch API instead of Axios, fetch-retry is an excellent alternative for implementing retry logic.

  • retry-request is a library that provides retry functionality for HTTP requests made with various libraries, including Axios and the native HTTP module in Node.js. It offers a flexible API for configuring retries and can be used in both browser and server environments. If you need a more generalized solution that works across different HTTP clients, retry-request might be the right choice.

  • superagent-retry is an extension for Superagent, another popular HTTP client. This library adds retry capabilities to Superagent requests, allowing developers to specify retry conditions and delays. If your project is already using Superagent, superagent-retry can easily integrate retry logic into your existing setup.

To see how retry-axios compares with axios-retry, fetch-retry, retry-request, and superagent-retry, check out the comparison: Comparing axios-retry vs fetch-retry vs retry-axios vs retry-request vs superagent-retry.

Similar Npm Packages to retry-request

retry-request is a utility library designed to enhance HTTP request capabilities by automatically retrying failed requests. It is particularly useful in scenarios where network reliability is a concern, such as in mobile applications or when interacting with unstable APIs. By implementing a retry mechanism, retry-request helps improve the resilience of applications, ensuring that transient errors do not disrupt user experience.

While retry-request provides a solid solution for retrying HTTP requests, there are several alternatives in the ecosystem that offer similar functionalities:

  • axios-retry is a popular library that integrates seamlessly with Axios, a widely-used HTTP client for JavaScript. It allows developers to automatically retry failed requests based on customizable conditions, such as specific HTTP status codes or network errors. If you are already using Axios in your application, axios-retry is a straightforward choice to add retry capabilities without significant overhead.

  • fetch-retry is a library that extends the native Fetch API to include retry functionality. It allows developers to specify retry conditions and delay intervals when making HTTP requests. If your application relies on the Fetch API and you want to add retry logic without switching to another HTTP client, fetch-retry is an excellent option.

  • requestretry is a library built on top of the popular request library for Node.js. It provides a simple way to retry HTTP requests with customizable options, including the number of retries and delay intervals. If you are working in a Node.js environment and prefer the request library, requestretry can easily enhance your request handling.

  • retry-axios is another library that adds retry functionality specifically for Axios. It is designed to be simple to use and provides options for customizing retry behavior, such as exponential backoff and retry limits. If you are looking for a robust solution for retrying requests with Axios, retry-axios is a strong contender.

  • superagent-retry is an extension for Superagent, a popular HTTP request library. It adds retry capabilities to Superagent requests, allowing developers to specify retry conditions and intervals. If you are using Superagent in your project, this library can easily integrate retry logic into your existing request handling.

To explore how these libraries compare, visit: Comparing axios-retry vs fetch-retry vs requestretry vs retry-axios vs retry-request vs superagent-retry.

README for backoff

Backoff for Node.js

Build Status NPM version

Fibonacci and exponential backoffs for Node.js.

Installation

npm install backoff

Unit tests

npm test

Usage

Object Oriented

The usual way to instantiate a new Backoff object is to use one predefined factory method: backoff.fibonacci([options]), backoff.exponential([options]).

Backoff inherits from EventEmitter. When a backoff starts, a backoff event is emitted and, when a backoff ends, a ready event is emitted. Handlers for these two events are called with the current backoff number and delay.

var backoff = require('backoff');

var fibonacciBackoff = backoff.fibonacci({
    randomisationFactor: 0,
    initialDelay: 10,
    maxDelay: 300
});

fibonacciBackoff.failAfter(10);

fibonacciBackoff.on('backoff', function(number, delay) {
    // Do something when backoff starts, e.g. show to the
    // user the delay before next reconnection attempt.
    console.log(number + ' ' + delay + 'ms');
});

fibonacciBackoff.on('ready', function(number, delay) {
    // Do something when backoff ends, e.g. retry a failed
    // operation (DNS lookup, API call, etc.). If it fails
    // again then backoff, otherwise reset the backoff
    // instance.
    fibonacciBackoff.backoff();
});

fibonacciBackoff.on('fail', function() {
    // Do something when the maximum number of backoffs is
    // reached, e.g. ask the user to check its connection.
    console.log('fail');
});

fibonacciBackoff.backoff();

The previous example would print the following.

0 10ms
1 10ms
2 20ms
3 30ms
4 50ms
5 80ms
6 130ms
7 210ms
8 300ms
9 300ms
fail

Note that Backoff objects are meant to be instantiated once and reused several times by calling reset after a successful "retry".

Functional

It's also possible to avoid some boilerplate code when invoking an asynchronous function in a backoff loop by using backoff.call(fn, [args, ...], callback).

Typical usage looks like the following.

var call = backoff.call(get, 'https://duplika.ca/', function(err, res) {
    console.log('Num retries: ' + call.getNumRetries());

    if (err) {
        console.log('Error: ' + err.message);
    } else {
        console.log('Status: ' + res.statusCode);
    }
});

call.retryIf(function(err) { return err.status == 503; });
call.setStrategy(new backoff.ExponentialStrategy());
call.failAfter(10);
call.start();

API

backoff.fibonacci([options])

Constructs a Fibonacci backoff (10, 10, 20, 30, 50, etc.).

The options are the following.

  • randomisationFactor: defaults to 0, must be between 0 and 1
  • initialDelay: defaults to 100 ms
  • maxDelay: defaults to 10000 ms

With these values, the backoff delay will increase from 100 ms to 10000 ms. The randomisation factor controls the range of randomness and must be between 0 and 1. By default, no randomisation is applied on the backoff delay.

backoff.exponential([options])

Constructs an exponential backoff (10, 20, 40, 80, etc.).

The options are the following.

  • randomisationFactor: defaults to 0, must be between 0 and 1
  • initialDelay: defaults to 100 ms
  • maxDelay: defaults to 10000 ms
  • factor: defaults to 2, must be greater than 1

With these values, the backoff delay will increase from 100 ms to 10000 ms. The randomisation factor controls the range of randomness and must be between 0 and 1. By default, no randomisation is applied on the backoff delay.

backoff.call(fn, [args, ...], callback)

  • fn: function to call in a backoff handler, i.e. the wrapped function
  • args: function's arguments
  • callback: function's callback accepting an error as its first argument

Constructs a FunctionCall instance for the given function. The wrapped function will get retried until it succeds or reaches the maximum number of backoffs. In both cases, the callback function will be invoked with the last result returned by the wrapped function.

It is the caller's responsability to initiate the call by invoking the start method on the returned FunctionCall instance.

Class Backoff

new Backoff(strategy)

  • strategy: the backoff strategy to use

Constructs a new backoff object from a specific backoff strategy. The backoff strategy must implement the BackoffStrategyinterface defined bellow.

backoff.failAfter(numberOfBackoffs)

  • numberOfBackoffs: maximum number of backoffs before the fail event gets emitted, must be greater than 0

Sets a limit on the maximum number of backoffs that can be performed before a fail event gets emitted and the backoff instance is reset. By default, there is no limit on the number of backoffs that can be performed.

backoff.backoff([err])

Starts a backoff operation. If provided, the error parameter will be emitted as the last argument of the backoff and fail events to let the listeners know why the backoff operation was attempted.

An error will be thrown if a backoff operation is already in progress.

In practice, this method should be called after a failed attempt to perform a sensitive operation (connecting to a database, downloading a resource over the network, etc.).

backoff.reset()

Resets the backoff delay to the initial backoff delay and stop any backoff operation in progress. After reset, a backoff instance can and should be reused.

In practice, this method should be called after having successfully completed the sensitive operation guarded by the backoff instance or if the client code request to stop any reconnection attempt.

Event: 'backoff'

  • number: number of backoffs since last reset, starting at 0
  • delay: backoff delay in milliseconds
  • err: optional error parameter passed to backoff.backoff([err])

Emitted when a backoff operation is started. Signals to the client how long the next backoff delay will be.

Event: 'ready'

  • number: number of backoffs since last reset, starting at 0
  • delay: backoff delay in milliseconds

Emitted when a backoff operation is done. Signals that the failing operation should be retried.

Event: 'fail'

  • err: optional error parameter passed to backoff.backoff([err])

Emitted when the maximum number of backoffs is reached. This event will only be emitted if the client has set a limit on the number of backoffs by calling backoff.failAfter(numberOfBackoffs). The backoff instance is automatically reset after this event is emitted.

Interface BackoffStrategy

A backoff strategy must provide the following methods.

strategy.next()

Computes and returns the next backoff delay.

strategy.reset()

Resets the backoff delay to its initial value.

Class ExponentialStrategy

Exponential (10, 20, 40, 80, etc.) backoff strategy implementation.

new ExponentialStrategy([options])

The options are the following.

  • randomisationFactor: defaults to 0, must be between 0 and 1
  • initialDelay: defaults to 100 ms
  • maxDelay: defaults to 10000 ms
  • factor: defaults to 2, must be greater than 1

Class FibonacciStrategy

Fibonnaci (10, 10, 20, 30, 50, etc.) backoff strategy implementation.

new FibonacciStrategy([options])

The options are the following.

  • randomisationFactor: defaults to 0, must be between 0 and 1
  • initialDelay: defaults to 100 ms
  • maxDelay: defaults to 10000 ms

Class FunctionCall

This class manages the calling of an asynchronous function within a backoff loop.

This class should rarely be instantiated directly since the factory method backoff.call(fn, [args, ...], callback) offers a more convenient and safer way to create FunctionCall instances.

new FunctionCall(fn, args, callback)

  • fn: asynchronous function to call
  • args: an array containing fn's args
  • callback: fn's callback

Constructs a function handler for the given asynchronous function.

call.isPending()

Returns whether the call is pending, i.e. hasn't been started.

call.isRunning()

Returns whether the call is in progress.

call.isCompleted()

Returns whether the call is completed.

call.isAborted()

Returns whether the call is aborted.

call.setStrategy(strategy)

  • strategy: strategy instance to use, defaults to FibonacciStrategy.

Sets the backoff strategy to use. This method should be called before call.start() otherwise an exception will be thrown.

call.failAfter(maxNumberOfBackoffs)

  • maxNumberOfBackoffs: maximum number of backoffs before the call is aborted

Sets the maximum number of backoffs before the call is aborted. By default, there is no limit on the number of backoffs that can be performed.

This method should be called before call.start() otherwise an exception will be thrown..

call.retryIf(predicate)

  • predicate: a function which takes in as its argument the error returned by the wrapped function and determines whether it is retriable.

Sets the predicate which will be invoked to determine whether a given error should be retried or not, e.g. a network error would be retriable while a type error would stop the function call. By default, all errors are considered to be retriable.

This method should be called before call.start() otherwise an exception will be thrown.

call.getLastResult()

Returns an array containing the last arguments passed to the completion callback of the wrapped function. For example, to get the error code returned by the last call, one would do the following.

var results = call.getLastResult();
// The error code is the first parameter of the callback.
var error = results[0];

Note that if the call was aborted, it will contain the abort error and not the last error returned by the wrapped function.

call.getNumRetries()

Returns the number of times the wrapped function call was retried. For a wrapped function that succeeded immediately, this would return 0. This method can be called at any point in time during the call life cycle, i.e. before, during and after the wrapped function invocation.

call.start()

Initiates the call the wrapped function. This method should only be called once otherwise an exception will be thrown.

call.abort()

Aborts the call and causes the completion callback to be invoked with an abort error if the call was pending or running; does nothing otherwise. This method can safely be called mutliple times.

Event: 'call'

  • args: wrapped function's arguments

Emitted each time the wrapped function is called.

Event: 'callback'

  • results: wrapped function's return values

Emitted each time the wrapped function invokes its callback.

Event: 'backoff'

  • number: backoff number, starts at 0
  • delay: backoff delay in milliseconds
  • err: the error that triggered the backoff operation

Emitted each time a backoff operation is started.

Event: 'abort'

Emitted when a call is aborted.

Annotated source code

The annotated source code can be found at mathieuturcotte.github.io/node-backoff/docs.

License

This code is free to use under the terms of the MIT license.

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