Laurence

A simple cache for offline development.

in short

1. add Laurence to your app: import "laurence";
2. make some network requests using fetch()
3. disconnect from the internet
4. make those same network requests again successfully

motivation

Sometimes you:

• don’t have internet, but want to work on something that makes network requests.
• do have internet, but want work without getting distracted.

Laurence works by caching your requests into localStorage and replaying them while your internet is offline. Laurence only caches successful requests, and checks navigator.onLine to determine whether or not you’re connected to the internet.

Laurence works by wrapping fetch(), so you may want to use a fetch polyfill.

installation

In your terminal,

npm install --save-dev laurence

and in your app,

import "whatwg-fetch"; // Make sure any fetch polyfill you use comes first.
import "laurence";     // Please don’t rely on this in prod though. That’s a terrible idea.

some important notes

There’s a lot that you should know about Laurence.

Laurence isn’t for production

Laurence is meant as a development tool, not as a production cache.

I wrote Laurence at an airport in way less time than it should take to build something production-ready, so please don’t use this to actually cache parts of your app. Laurence has no logic for cache invalidation and doesn’t come with all the other niceties that you’d expect from a cache (like TTL or eviction policies).

Laurence stores URLs as plain text in localStorage

This probably isn’t be a big deal, but you’ll want to make sure you’re thoughtful about requests with API keys in them. They’ll sit around in your localStorage until you manually evict them. In the future, cache keys may be hashed which will make this a non-problem.

Laurence caches requests based on URLs and request methods

Meaning GET https://mozilla.org and POST https://mozilla.org are considered to be different. This method should work for most use cases, but it most notably won’t work when your requests rely on headers. Speaking of,

Laurence doesn’t cache headers

This is still something that needs to be implemented. For now, Laurence just caches status, status text, and the actual body (which it reads out and persists as text).