Retry Strategies

All strategies implement the RetryStrategy interface:

interface RetryStrategy {
  computeDelay(attempt: number, error?: unknown): number
}

Delays are validated at construction: a negative delay used to make setTimeout fire immediately, producing a retry storm with no back-off at all.

Whether an error is retried at all is decided separately from the delay — see what gets retried, which depends on the HTTP method.

---

FixedRetryStrategy

new FixedRetryStrategy(delayMs: number)

Returns the same delay on every attempt.

import { FixedRetryStrategy } from 'super-http'
client.retry(3, new FixedRetryStrategy(500))
// → 500ms, 500ms, 500ms

---

ExponentialRetryStrategy

new ExponentialRetryStrategy(
  initialDelayMs: number,
  maxDelayMs: number = 30_000,
  factor: number = 2
)

Delay = min(initialDelayMs × factor^attempt, maxDelayMs)

import { ExponentialRetryStrategy } from 'super-http'
client.retry(4, new ExponentialRetryStrategy(100, 10_000))
// → 100ms, 200ms, 400ms, 800ms

---

ExponentialJitterRetryStrategy ⭐

new ExponentialJitterRetryStrategy(
  initialDelayMs: number,
  maxDelayMs: number = 30_000,
  factor: number = 2
)

Delay = random(0, min(initialDelayMs × factor^attempt, maxDelayMs))

Full-jitter prevents thundering-herd. Recommended for distributed systems.

import { ExponentialJitterRetryStrategy } from 'super-http'
client.retry(4, new ExponentialJitterRetryStrategy(100, 10_000))
// → random in [0–100ms], [0–200ms], [0–400ms], [0–800ms]

---

RetryAfterStrategy

new RetryAfterStrategy(
  initialDelayMs: number = 200,
  maxDelayMs: number = 60_000,
  factor: number = 2
)

Reads the Retry-After response header. Falls back to exponential jitter.

The parsed header is capped at maxDelayMs — the header is the server's number, not your budget, so Retry-After: 3600 must not park the caller for an hour.

import { RetryAfterStrategy } from 'super-http'
client.retry(5, new RetryAfterStrategy())
// Server: Retry-After: 30    → wait 30 000ms
// Server: Retry-After: 3600  → capped at maxDelayMs (60 s by default)
// Server: (no header)        → exponential jitter fallback

---

Custom strategy

import { RetryStrategy } from 'super-http'

class LinearRetryStrategy implements RetryStrategy {
  constructor(private readonly stepMs: number) {}
  computeDelay(attempt: number): number {
    return this.stepMs * (attempt + 1)
  }
}

client.retry(4, new LinearRetryStrategy(200))
// → 200ms, 400ms, 600ms, 800ms