Request Deduplication

Deduplication is provided as an optional plugin.

For the canonical option/type reference, see api.md -> Deduplication Plugin.

Import

import { createClient } from '@fetchkit/ffetch'
import {
  dedupePlugin,
  dedupeRequestHash,
} from '@fetchkit/ffetch/plugins/dedupe'

Usage

const client = createClient({
  plugins: [dedupePlugin()],
})

const p1 = client('https://api.example.com/data')
const p2 = client('https://api.example.com/data')
const [r1, r2] = await Promise.all([p1, p2])
// One network request, shared in-flight promise.

Configuration

const client = createClient({
  plugins: [
    dedupePlugin({
      hashFn: (params) => `${params.method}|${params.url}|${params.body}`,
      ttl: 30_000,
      sweepInterval: 5_000,
    }),
  ],
})

Options

• hashFn: Custom key function. Return undefined to skip dedupe for a request.
• ttl: Optional map-entry eviction TTL in milliseconds.
• sweepInterval: Sweeper interval in milliseconds when ttl is enabled.
• order: Plugin execution order override.

Behavior Notes

• Deduplication is off unless the plugin is installed.
• The dedupe key is computed from the original request init/body before dispatch; if transformRequest changes request identity, use a custom hashFn that reflects the final semantics you need.
• TTL eviction only removes in-flight dedupe keys from the map.
• TTL eviction does not reject already in-flight request promises.
• Stream/FormData request bodies are skipped by the default hash strategy.

Defaults

• hashFn: dedupeRequestHash
• ttl: undefined (disabled)
• sweepInterval: 5000
• order: 10

Breaking Migration

Removed legacy options:

• dedupe
• dedupeHashFn
• dedupeTTL
• dedupeSweepInterval

Use plugins: [dedupePlugin(...)] instead.