cached-observable

A simple utility to cache RxJS Observables in memory, Session and Local Storage

This utility allows you to cache streams in memory, or Web Storage. It also
works in Node, but please only use in-memory if you do so.

In the future, it will be extended with he ability provide a way to provide a
custom CacheProviderType,
such as Redis.

Install

``bash
npm i cached-observable --save
`

Usage

$3

The utility has the following interface:

`typescript
function cachedObservable(
observable$: Observable,
key: string,
maxAge?: number | undefined,
cacheProviderType = CacheProviderType.Memory,
)
`

- observable$ is the stream we want to cache
- key is a unique key - please make sure it is unique
- maxAge is a value, in milliseconds, that represents the amount of time the
value will be cached for
- cacheProviderType is by default in-memory, you can also choose
CacheProviderType.Persistent or CacheProviderType.Session

$3

A basic example; the stream is cached in memory for the whole duration of
the session.

`typescript
import { cachedObservable } from 'cached-observable';

function getTodos() {
const request$ = this.http.get(url);
const key = url;

return cachedObservable(request$, key);
}
`

$3

We can set a max-age - so that the entry will expire after the number of
milliseconds provided

`typescript
import { cachedObservable } from 'cached-observable';

function getTodos() {
const request$ = this.http.get(url);
const key = url;
const maxAge = 60_000; // 1 minute

return cachedObservable(request$, key, maxAge);
}
`

$3

We can store the streams in both session and local storage:

`typescript
import { cachedObservable, CacheProviderType } from 'cached-observable';

// local storage
function getTodos() {
const request$ = this.http.get(url);

return cachedObservable(request$, url, maxAge, CacheProviderType.Persistent);
}

// session storage
function getTodos() {
const request$ = this.http.get(url);

return cachedObservable(request$, url, maxAge, CacheProviderType.Session);
}
`

$3

`typescript
import { invalidateCachedObservable } from 'cached-observable';

invalidateCachedObservable(cacheKey, CacheProviderType.Session);
``