TempBox

TempBox is a lightweight, in-memory key-value store for Node.js with built-in TTL (time-to-live) support and proactive expiration. It's not a cache—it's a tiny ephemeral store that keeps your data just long enough, and then lets it go.

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✨ Features

• 🧠 In-memory, in-process store
• ⏳ Per-key TTL support (milliseconds)
• ⏱️ Proactive expiration (via setTimeout, not lazy)
• 🔔 Optional onExpire callback
• 🚫 No LRU, no persistence, no external dependencies (except for tinyqueue)

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🚀 Installation

npm install tempbox

🧰 Usage

import { TempBox } from "tempbox";

const store = new TempBox();

store.set("session:123", { userId: 1 }, 3000); // expires in 3 seconds
store.set("token:abc", "xyz"); // no expiration

console.log(store.get("session:123")); // { userId: 1 }

setTimeout(() => {
  console.log(store.get("session:123")); // undefined (expired)
}, 3100);

🔔 Expiration Callback

You can provide a callback that runs when keys expire:

const store = new TempBox({
  onExpire: (key, value) => {
    console.log(`Expired: ${key} →`, value);
  },
});

🧪 API

new TempBox(options?)

Creates a new instance of the store.

Available options:

Option	Type	Default	Description
onExpire	(key: string, value: any) => void	undefined	Callback invoked when a key expires

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store.set(key: string, value: any, ttlMs?: number): void

Stores a key with an optional TTL in milliseconds. If no TTL is provided, the value will not expire automatically.

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store.get(key: string): any | undefined

Returns the stored value if it exists and hasn't expired. If the key has expired, it will be removed and undefined is returned.

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store.has(key: string): boolean

Returns true if the key exists and hasn't expired, false otherwise.

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store.delete(key: string): boolean

Manually removes a key. Returns true if the key existed and was deleted, false otherwise.

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store.stop(): void

Stops the internal expiration timers. Useful for graceful shutdown or during testing.

⚠️ Not a Cache

TempBox is not a cache. It's not optimized for size or eviction strategies (e.g. LRU). It's built for situations where you just want to store small pieces of data for a limited time, entirely in memory.

🪶 Lightweight

TempBox only uses tinyqueue internally for efficient scheduling of expirations. No other dependencies.

📄 License

MIT 2025 - José F. Romaniello