Rate limiting utility

A relatively simple utility for abstract rate limiting. This library uses memory storage (i.e. does not rely on external database or writing data on your file system). Rate limits are reset if the process is restarted.

Get started

Install package from npm

npm i cldn-ratelimit

Import in your project

Here is a very simple demo demonstrating very basic limiting of login attempts.

import {RateLimit} from 'cldn-ratelimit';

const rateLimit = new RateLimit("login-attempts", 3, 60); // max 3 requests per 60 seconds

const attemptLogin = (username, password) => {
	if (!rateLimit.attempt(username).allow) return "rate-limited";
	if (username === "john.doe" && password === "password123") return "success";
	return "wrong-password";
}

attemptLogin("john.doe", "wrongpass"); //-> "wrong-password"
attemptLogin("john.doe", "wrongpass2"); //-> "wrong-password"
attemptLogin("john.doe", "wrongpass"); //-> "wrong-password"
attemptLogin("john.doe", "password123"); //-> "rate-limited"
// wait 60 seconds
attemptLogin("john.doe", "password123"); //-> "success"

If you want to reset the rate limit after a successful login, call rateLimit.reset(username).

Documentation

Table of contents

• Class: RateLimit
  • Static method: RateLimit.attempt(name, source, [attempts], [callback])
  • Static method: RateLimit.check(name, source, [callback])
  • Static method: RateLimit.clear(name)
  • Static method: RateLimit.create(name, limit, timeWindow)
  • Static method: RateLimit.delete(name)
  • Static method: RateLimit.get(name)
  • Static method: RateLimit.reset(name, source)
  • Static method: RateLimit.setRemaining(name, source, remaining)
  • new RateLimit(name, limit, timeWindow)
  • rateLimit.attempt(source, [attempts], [callback])
  • rateLimit.check(source, [callback])
  • rateLimit.clear()
  • rateLimit.delete()
  • rateLimit.limit
  • rateLimit.name
  • rateLimit.reset(source)
  • rateLimit.setRemaining(source, remaining)
  • rateLimit.timeWindow
• Interface: AttemptResult
  • attemptResult.limit
  • attemptResult.remaining
  • attemptResult.reset
  • attemptResult.rateLimit
  • attemptResult.allow

Class: RateLimit

Rate limit

Static method: RateLimit.attempt(name, source, [attempts], [callback])

Make an attempt with a source ID

• name string The name of the rate limit
• source string Unique source identifier (e.g. username, IP, etc.)
• attempts number The number of attempts to make. Default: 1
• callback function Callback function. Default: undefined
  • result AttemptResult The result of the attempt
  • Returns: void
• Returns: AttemptResult
• Throws: Error If the rate limit does not exist

Static method: RateLimit.check(name, source, [callback])

Check the attempt state for a source ID without decrementing the remaining attempts

• name string The name of the rate limit
• source string Unique source identifier (e.g. username, IP, etc.)
• callback function Callback function. Default: undefined
  • result AttemptResult The result of the attempt
  • Returns: void
• Returns: AttemptResult
• Throws: Error If the rate limit does not exist

Static method: RateLimit.clear(name)

Clear rate limit attempts storage. This is equivalent to resetting all rate limits.

• name string The name of the rate limit
• Returns: void
• Throws: Error If the rate limit does not exist

Static method: RateLimit.create(name, limit, timeWindow)

Create a new rate limit

• name string The name of the rate limit
• limit number The number of attempts allowed per time window (e.g. 60)
• timeWindow number The time window in seconds (e.g. 60)
• Returns: RateLimit

Static method: RateLimit.delete(name)

Delete the rate limit instance. After it is deleted, it should not be used any further without constructing a new instance.

• name string The name of the rate limit
• Returns: void
• Throws: Error If the rate limit does not exist

Static method: RateLimit.get(name)

Get a rate limit instance

• name string The name of the rate limit
• Returns: RateLimit or null

Static method: RateLimit.reset(name, source)

Reset limit for a source ID. The storage entry will be deleted and a new one will be created on the next attempt.

• name string The name of the rate limit
• source string Unique source identifier (e.g. username, IP, etc.)
• Returns: void
• Throws: Error If the rate limit does not exist

Static method: RateLimit.setRemaining(name, source, remaining)

Set the remaining attempts for a source ID.

Warning: This is not recommended as the remaining attempts depend on the limit of the instance.

• name string The name of the rate limit
• source string Unique source identifier (e.g. username, IP, etc.)
• remaining number The number of remaining attempts
• Returns: void
• Throws: Error If the rate limit does not exist

new RateLimit(name, limit, timeWindow)

Create a new rate limit

• name string The name of the rate limit
• limit number The number of attempts allowed per time window (e.g. 60)
• timeWindow number The time window in seconds (e.g. 60)
• Throws: Error If the rate limit already exists

rateLimit.attempt(source, [attempts], [callback])

Make an attempt with a source ID

• source string Unique source identifier (e.g. username, IP, etc.)
• attempts number The number of attempts to make. Default: 1
• callback function Callback function
  • result AttemptResult The result of the attempt
  • Returns: void
• Returns: AttemptResult

rateLimit.check(source, [callback])

Check the attempt state for a source ID without decrementing the remaining attempts

• source string Unique source identifier (e.g. username, IP, etc.)
• callback function Callback function
  • result AttemptResult The result of the attempt
  • Returns: void
• Returns: AttemptResult

rateLimit.clear()

Clear rate limit attempts storage. This is equivalent to resetting all rate limits.

• Returns: void

rateLimit.delete()

Delete the rate limit instance. After it is deleted, it should not be used any further without constructing a new instance.

• Returns: void

rateLimit.limit

The number of requests allowed per time window

• Type: number

rateLimit.name

Get rate limit name

• Type: string
• Readonly

rateLimit.reset(source)

Reset limit for a source ID. The storage entry will be deleted and a new one will be created on the next attempt.

• source string Unique source identifier (e.g. username, IP, etc.)
• Returns: void

rateLimit.setRemaining(source, remaining)

Set the remaining attempts for a source ID.

Warning: This is not recommended as the remaining attempts depend on the limit of the instance.

• source string Unique source identifier (e.g. username, IP, etc.)
• remaining number The number of remaining attempts
• Returns: void

rateLimit.timeWindow

The time window in seconds (e.g. 60)

• Type: number

Interface: AttemptResult

The result from a rate limit attempt

attemptResult.limit

The number of requests this rate limit allows per time window

• Type: number
• Readonly

attemptResult.remaining

The number of requests remaining in the current time window

• Type: number
• Readonly

attemptResult.reset

The number of seconds until the current time window resets

• Type: number
• Readonly

attemptResult.rateLimit

The rate limit that this attempt was made on

• Type: RateLimit
• Readonly

attemptResult.allow

Whether this attempt should be allowed to proceed. If false, the attempt is rate limited.

• Type: boolean
• Readonly