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Stateful Objects

JavaScript/TypeScript native W7S backends can declare stateful object classes in w7s.json. W7S creates persistent classes the first time it sees them and binds each class to the backend by name.

Working example repository:

Declare a stateful object​

Add bindings.durableObjects to w7s.json:

w7s.json
{
  "bindings": {
    "durableObjects": [
      {
        "binding": "COUNTER",
        "className": "Counter"
      }
    ]
  }
}

The backend must export the class named by className.

Implement the class​

backend/index.js
export class Counter {
  constructor(ctx) {
    this.ctx = ctx;
  }

  async fetch(request) {
    const count = (await this.ctx.storage.get("count")) ?? 0;

    if (new URL(request.url).pathname === "/increment") {
      await this.ctx.storage.put("count", count + 1);
      return Response.json({ count: count + 1 });
    }

    return Response.json({ count });
  }
}

export default {
  fetch(request, env) {
    const id = env.COUNTER.idFromName("global");
    return env.COUNTER.get(id).fetch(request);
  }
};

Redeploy behavior​

Stateful object apps use a stable runtime identity for each GitHub owner, repo, and environment. This is different from regular JavaScript/TypeScript native backends, which use commit-specific runtime identities.

The stable identity is what lets state survive W7S redeploys.

W7S automatically creates newly declared persistent classes. It does not automate class renames, transfers, or deletes yet.

Live example​

The example workflow reads the current counter, increments it twice, and verifies the new value after deploy. That proves the stateful binding works and state persists across W7S redeploys.