Rate Limit Module

The std/rate_limit module provides in-memory rate limiting with configurable time windows and request limits.

Import

import { rateLimit } from "std/rate_limit"

Functions

rateLimit.create(limit: int, windowMs: int): string

Create a new rate limiter. Returns a limiter ID for use with other functions.

• limit — maximum number of requests allowed in the window
• windowMs — time window in milliseconds

// Allow 100 requests per minute
const limiter = rateLimit.create(100, 60000)

// Allow 10 requests per second
const strictLimiter = rateLimit.create(10, 1000)

rateLimit.check(limiterID: string, key: string): bool

Check if a request is allowed for the given key. Returns true if allowed, false if rate-limited. The key is typically an IP address or user ID.

const allowed = rateLimit.check(limiter, "192.168.1.1")
if (!allowed) {
    println("Rate limited!")
}

rateLimit.remaining(limiterID: string, key: string): int

Returns the number of remaining requests for the given key in the current window.

const left = rateLimit.remaining(limiter, "192.168.1.1")
println("Requests remaining: " + string(left))

rateLimit.reset(limiterID: string, key?: string): void

Reset the rate limiter. If a key is provided, resets only that key. Otherwise resets all keys.

rateLimit.reset(limiter, "192.168.1.1") // Reset one key
rateLimit.reset(limiter)                 // Reset all keys

Function Reference

Function	Description
rateLimit.create(limit, windowMs)	Create a new rate limiter
rateLimit.check(limiterID, key)	Check if request is allowed
rateLimit.remaining(limiterID, key)	Get remaining requests for key
rateLimit.reset(limiterID, key?)	Reset limiter for key or all keys

Example: API Rate Limiting Middleware

import { rateLimit } from "std/rate_limit"
import { createServer, Request, Response } from "std/http"

const app = createServer()

// 100 requests per minute per IP
const limiter = rateLimit.create(100, 60000)

app.use(function(req: Request, res: Response, next: any) {
    const ip = req.headers["X-Forwarded-For"]
    const allowed = rateLimit.check(limiter, ip)

    if (!allowed) {
        const remaining = rateLimit.remaining(limiter, ip)
        res.header("X-RateLimit-Remaining", string(remaining))
        res.status(429).json('{"error": "Too many requests"}')
        return
    }

    next()
})

app.get("/api/data", function(req: Request, res: Response): Response {
    return res.json('{"message": "Hello"}')
})

app.listen(3000)