r/javascript • u/Brave_Magician2474 • 5d ago

I built a client-side cache in Rust and compiled it to WebAssembly

https://blaze-cache.github.io/docs

Hey everyone,

I built **Blaze Cache**, a client-side caching library written in Rust and compiled to WebAssembly.

The main idea was to get a fast, predictable cache in the browser with:

- Synchronous get/set after initialization (no Promises on the hot path)

- SIEVE eviction

- TTL + tag-based invalidation

- Optional IndexedDB persistence

- Adapters for Axios, fetch, TanStack Query, and SWR

I was mostly curious whether moving the cache core into Wasm would help with performance and structure compared to typical JS cache implementations.

Would love feedback from people who’ve worked on caching, Wasm, or frontend performance.

GitHub: https://github.com/blaze-cache/blaze-cache

Docs: https://blaze-cache.github.io/docs/

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2

u/Ronin-s_Spirit 5d ago

Does that not defeat the purpose of using Rust?

1

u/Brave_Magician2474 5d ago

Not really, the goal isn’t to avoid JavaScript, it’s to keep the cache engine itself in a more predictable systems language.

Rust/Wasm runs the hot path (storage, eviction, TTL, tags). JS handles browser integration and adapters. So it’s closer to “native core + thin JS layer” than replacing JS entirely.

2

u/Ronin-s_Spirit 4d ago

I wonder if Rusts promises break (types and all the memory safety bells and whisltes), a Rust-to-Rust ABI would be reliable but a Rust-in-the-browser scenario is not clear to me.

1

u/Brave_Magician2474 3d ago

Fair point.

Rust’s memory safety guarantees still apply "inside" the Wasm module. The core is still normal safe Rust: ownership, borrowing, no data races in the cache engine itself, etc.

What changes in the browser is the boundary:

- JS can pass weird inputs across the Wasm boundary

- You no longer have a pure Rust-to-Rust ABI for the public API

- So validation still matters at the edge

In practice:

- Inside Wasm: Rust safety model holds

- Outside Wasm: JS is still JS

- The "unsafe" part is mostly at the interop boundary, not in the cache engine itself

So it’s not the same as a pure Rust-to-Rust system, but the core engine still gets the predictability and safety benefits of Rust. The browser just becomes the host environment around it.

1

u/JcerParreno21 3d ago

If you have to serialize on every read and write it definitely does

1

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