# Rate Limiter Algorithms

A rate limiting library that provides various algorithms and works in any Javascript environment.\
You can find more information about algorithms in [this article](https://medium.com/@Neirea_/rate-limiting-algorithms-d97d0a8bd99d).

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](LICENSE)

## Example with Node.js

```ts
import { createServer } from "node:http";
import { RateLimiter } from "rate-limiter-algorithms";

const limiter = new RateLimiter({
    algorithm: "token-bucket",
    limit: 5,
    windowMs: 5000,
});

const server = createServer(async (req, res) => {
    const uniqueKey = req.socket.remoteAddress; // or any other unique key like userId

    try {
        const { isAllowed, clientData } = await limiter.consume(uniqueKey);

        // set rate limiting headers
        const headers = limiter.getHeaders(clientData);
        for (const header of headers) {
            res.setHeader(header[0], header[1]);
        }

        if (!isAllowed) {
            res.writeHead(429, "Too many requests");
            res.end("Failure");
            return;
        }
        res.end("Success");
    } catch (error) {
        console.error("Error in rate limiting:", error);
    }
});

server.listen(3000, "127.0.0.1", () => {
    console.log("Listening on 127.0.0.1:3000");
});
```

## Config

| Option      | Type     | Explanation                                                                                     |
| ----------- | -------- | ----------------------------------------------------------------------------------------------- |
| `algorithm` | `string` | Values: `token-bucket`, `fixed-window-counter`, `sliding-window-logs`, `sliding-window-counter` |
| `windowMs`  | `number` | Duration of time in milliseconds when algorithm updates its counter.                            |
| `limit`     | `number` | Maximum amount of points that client can consume                                                |
| `store`     | `Store`  | Store which contains clients data based on chosen algorithm. Defaults to Memory Store           |

## Date Stores

### Memory Store

Default in-memory option. Example:

```ts
import { RateLimiter, MemoryStore } from "rate-limiter-algorithms";

const limiter = new RateLimiter({
    algorithm: "token-bucket",
    limit: 5,
    windowMs: 5000,
    store: new MemoryStore(), // defaults to this value if unspecified
});
```

### Redis Store

Uses **rawCall** function to send raw commands to **Redis**. Example for [`node-redis`](https://github.com/redis/node-redis) :

```ts
import { RateLimiter, RedisStore } from "rate-limiter-algorithms";
import { createClient } from "redis";

const client = createClient();
client.connect();

const limiter = new RateLimiter({
    algorithm: "token-bucket",
    limit: 5,
    windowMs: 5000,
    store: new RedisStore({
        prefix: "rla:", // defaults to this value if unspecified
        rawCall: (...args: string[]) => client.sendCommand(args),
    }),,
});
```

Raw command list:

| Library                                             | Function                                                                |
| --------------------------------------------------- | ----------------------------------------------------------------------- |
| [`node-redis`](https://github.com/redis/node-redis) | `(...args: string[]) => client.sendCommand(args)`                       |
| [`ioredis`](https://github.com/luin/ioredis)        | `(command: string, ...args: string[]) => client.call(command, ...args)` |

## License

All code and documentation are (c) 2024-Present [Eugene Shumilin](https://github.com/Neirea) and released under the [MIT License](LICENSE)