exponential-backoff

A utility that allows retrying a function with an exponential delay between attempts.

Installation

npm i exponential-backoff

Usage

The backOff<T> function takes a promise-returning function to retry, and an optional BackOffOptions object. It returns a Promise<T>.

1function backOff<T>(
2  request: () => Promise<T>,
3  options?: BackOffOptions
4): Promise<T>;

Here is an example retrying a function that calls a hypothetical weather endpoint:

1import { backOff } from "exponential-backoff";
2
3function getWeather() {
4  return fetch("weather-endpoint");
5}
6
7async function main() {
8  try {
9    const response = await backOff(() => getWeather());
10    // process response
11  } catch (e) {
12    // handle error
13  }
14}
15
16main();

Migrating across major versions? Here are our breaking changes.

BackOffOptions

• delayFirstAttempt?: boolean

  Decides whether the startingDelay should be applied before the first call. If false, the first call will occur without a delay.

  Default value is false.

• jitter?: JitterType | string

  Decides whether a jitter should be applied to the delay. Possible values are full and none.

  Default value is none.

• maxDelay?: number

  The maximum delay, in milliseconds, between two consecutive attempts.

  Default value is Infinity.

• numOfAttempts?: number

  The maximum number of times to attempt the function.

  Default value is 10.

  Minimum value is 1.

• retry?: (e: any, attemptNumber: number) => boolean | Promise<boolean>

  The retry function can be used to run logic after every failed attempt (e.g. logging a message, assessing the last error, etc.). It is called with the last error and the upcoming attempt number. Returning true will retry the function as long as the numOfAttempts has not been exceeded. Returning false will end the execution.

  Default value is a function that always returns true.

• startingDelay?: number

  The delay, in milliseconds, before executing the function for the first time.

  Default value is 100 ms.

• timeMultiple?: number

  The startingDelay is multiplied by the timeMultiple to increase the delay between reattempts.

  Default value is 2.