Cache read & write

The four basic read/write operations on the cache. All are static, all return Promises.

get

Returns the entry for key, or null if the key is absent or expired.

import { Cache } from 'fastedge::cache';

async function eventHandler(event) {
  const entry = await Cache.get('user:42');
  if (entry === null) {
    return new Response('Not found', { status: 404 });
  }
  const user = await entry.json();
  return Response.json(user);
}

addEventListener('fetch', (event) => {
  event.respondWith(eventHandler(event));
});

SYNTAX

Cache.get(key);

Parameters

• key (required)

  A string identifying the entry to retrieve.

Return Value

A Promise<CacheEntry | null>. The bytes are already in memory by the time the Promise resolves; the CacheEntry accessor methods (text, json, arrayBuffer) resolve immediately. See CacheEntry accessors below.

set

Stores a value under key, overwriting any existing entry. Optionally sets an expiry.

import { Cache } from 'fastedge::cache';

async function eventHandler(event) {
  await Cache.set('session:abc', JSON.stringify({ user: 42 }), { ttl: 600 });
  await Cache.set('manifest', await fetch('/manifest.json'));
  return new Response('ok');
}

addEventListener('fetch', (event) => {
  event.respondWith(eventHandler(event));
});

SYNTAX

Cache.set(key, value, options?);

Parameters

• key (required)

  A string identifying the entry to write.

• value (required)

  A CacheValue — string, ArrayBuffer, ArrayBufferView, ReadableStream, or Response. All forms are coerced to raw bytes before storage.

• options (optional)

  A WriteOptions object: { ttl }, { ttlMs }, or { expiresAt }. Omit (or pass {}) for no expiry.

Return Value

A Promise<void>.

delete

Removes the entry at key. A no-op if the key is already absent — no error is thrown.

import { Cache } from 'fastedge::cache';

async function eventHandler(event) {
  await Cache.delete('session:abc');
  return new Response('ok');
}

addEventListener('fetch', (event) => {
  event.respondWith(eventHandler(event));
});

SYNTAX

Cache.delete(key);

Parameters

• key (required)

  A string identifying the entry to remove.

Return Value

A Promise<void>.

exists

Tests whether a key is present without transferring its value. Cheaper than get when only presence matters (e.g. idempotency-key checks, “have we seen this token before?”).

import { Cache } from 'fastedge::cache';

async function eventHandler(event) {
  if (await Cache.exists('idempotency:abc')) {
    return new Response('Already processed', { status: 200 });
  }
  // ... do the work, then mark it as seen
  return new Response('ok');
}

addEventListener('fetch', (event) => {
  event.respondWith(eventHandler(event));
});

SYNTAX

Cache.exists(key);

Parameters

• key (required)

  A string identifying the entry to test.

Return Value

A Promise<boolean> — true if the key is present and unexpired, false otherwise.

CacheEntry accessors

Cache.get and Cache.getOrSet resolve to CacheEntry objects. The bytes are already in memory; the accessor methods are Promise-returning to align with the standard Web Body interface, but they resolve immediately.

Method	Signature	Description
text	(): Promise<string>	Read the entry as a UTF-8 decoded string
json	(): Promise<unknown>	Read the entry as parsed JSON
arrayBuffer	(): Promise<ArrayBuffer>	Read the entry as raw bytes

json rejects with a SyntaxError if the bytes are not valid JSON.