Spaces:
Running
Running
| # 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>`. | |
| ```ts | |
| function backOff<T>( | |
| request: () => Promise<T>, | |
| options?: BackOffOptions | |
| ): Promise<T>; | |
| ``` | |
| Here is an example retrying a function that calls a hypothetical weather endpoint: | |
| ```js | |
| import { backOff } from "exponential-backoff"; | |
| function getWeather() { | |
| return fetch("weather-endpoint"); | |
| } | |
| async function main() { | |
| try { | |
| const response = await backOff(() => getWeather()); | |
| // process response | |
| } catch (e) { | |
| // handle error | |
| } | |
| } | |
| main(); | |
| ``` | |
| Migrating across major versions? Here are our [breaking changes](https://github.com/coveo/exponential-backoff/tree/master/doc/migration-guide.md). | |
| ### `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](https://aws.amazon.com/blogs/architecture/exponential-backoff-and-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`. | |