retry

Retry an asynchronous function with exponential backoff on failure.

Signature

function retry<T>(
  fn: () => Promise<T>,
  options?: {
    times?: number;
    delay?: number;
    backoff?: number | ((attempt: number, delay: number) => number);
    signal?: AbortSignal;
  },
): Promise<T>;

Parameters

• fn – The asynchronous function to retry
• options.times – The number of retry attempts (default: 3)
• options.delay – The delay in milliseconds between retries (default: 250)
• options.backoff – Exponential backoff factor or custom function (default: 1, no backoff)
• options.signal – AbortSignal to allow canceling retries

Returns

The result of the asynchronous function.

Examples

Basic Usage

import { retry } from '@vielzeug/toolkit';
const result = await retry(() => fetchData(), { times: 3, delay: 1000 });

Exponential Backoff

import { retry } from '@vielzeug/toolkit';
const result = await retry(() => unreliableAPICall(), {
  times: 5,
  delay: 500,
  backoff: 2, // Delays: 500ms, 1000ms, 2000ms, 4000ms, 8000ms
});

With AbortSignal

import { retry } from '@vielzeug/toolkit';
const controller = new AbortController();
const result = await retry(() => fetchData(), {
  times: 3,
  delay: 1000,
  signal: controller.signal,
});
// Can abort from outside
controller.abort();

Custom Backoff Function

import { retry } from '@vielzeug/toolkit';
const result = await retry(() => fetchData(), {
  times: 4,
  delay: 1000,
  backoff: (attempt, delay) => delay * attempt, // Linear backoff
});

Robust API Call

import { retry } from '@vielzeug/toolkit';
async function fetchWithRetry(url: string) {
  return retry(
    async () => {
      const response = await fetch(url);
      if (!response.ok) {
        throw new Error(`HTTP ${response.status}`);
      }
      return response.json();
    },
    {
      times: 3,
      delay: 1000,
      backoff: 2,
    },
  );
}

Related

• attempt – Execute with error handling and retry
• predict – Add timeout with AbortSignal