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Introduction

ng-ncached is a lightweight, hierarchical in-memory cache for Angular applications, with TTL expiration, Observable integration, request deduplication and optional localStorage persistence with pluggable compression.

It packs the patterns most apps end up reinventing — caching HTTP results, deduplicating concurrent requests, expiring stale data, surviving page reloads — into a single injectable service.

Highlights​

  • Hierarchical cache — organise data into namespaces and sub-namespaces of any depth, backed by native Map instances.
  • Immutable by design — set() and get() always deep-clone via structuredClone, so cache state can never be mutated from the outside.
  • TTL on every entry — pass { ttl: ms } to set() and the entry expires automatically.
  • Observable caching — cacheObservable() wraps an HTTP call (or any Observable), caches the result, and deduplicates concurrent in-flight requests via shareReplay.
  • Safe accessors — getOrDefault() never throws; the rest throws typed errors you can discriminate with instanceof.
  • Invalidation API — remove(), clear(), clearAll() for fine-grained or full wipes.
  • Optional persistence — opt in to localStorage snapshots on beforeunload, with pluggable compression (NoopCompressor, LzStringCompressor, or your own).
  • Tree-shakeable, zero-config — just inject NcachedService. Provided in root.

When should I use it?​

Reach for ng-ncached when you want:

  • A shared in-memory cache across components and services without each owner reinventing keying / lookup / TTL.
  • Deduplication of concurrent HTTP calls hitting the same endpoint at the same time.
  • A simple way to make a slice of state survive page reloads, with optional compression to fit more in 5 MB of localStorage.

If you need cross-tab synchronisation, IndexedDB, or background workers, that's outside the scope — ng-ncached deliberately stays small and predictable.

What's next?​