JavaScript/Typescript multi-language curse word filter
npm install curse-filtercurse-filter is a fully-equipped Node.js library that simplifies profanity filtering in _15+ different languages_.
``bash`
npm install curse-filter
This module is first thought for Typescript/ESM, so this is the recommended way to load it.
`typescript`
import { filter } from 'curse-filter';
Profanity language is used in this README for demonstration purposes only. Please be respectful.
`typescript
import { supportedLangs } from 'curse-filter';
// This will log an array of supported languages
console.log(supportedLangs);
`
The filter() function asynchronously replaces curse words in a string with asterisks ("\\\*") or a custom placeholder.
`typescript
import { filter } from 'curse-filter';
// This must be used in an async function or top-level await context
await filter('fuck you');
// result: '* you'
await filter('fuck you', { lang: 'en' });
// result: '* you'
await filter('fuck you, coglione', { lang: ['en', 'it'] });
// result: ' you, '
await filter('fuck you, coglione', { lang: ['en', 'it'], placeholder: 'customPlaceholder' });
// result: 'customPlaceholder you, customPlaceholder'
`
#### Parameters
- str _(string)_ – The input string to filter.
- options _(optional)_ – An object with:
- lang _(string | string[] | true)_: One or more language codes (e.g., 'en', 'it', or ['en', 'it']). If omitted, all supported languages will be used. Note that the fewer languages you pass to the function's options object, the faster the filtering will be.
- placeholder _(string)_: The replacement string. Defaults to '\\\*'.
- customKeywords _(Set\
#### Returns
A Promise with the filtered string.
The detect() function asynchronously detects whether or not curse words are in a string.
`typescript
import { detect } from 'curse-filter';
// This must be used in an async function or top-level await context
await detect('fuck you');
// result: true
await detect('fuckyou');
// false (no space, not detected by default)
await detect('fuckyou', { rigidMode: true });
// true (rigid mode allows substring matching)
await detect('fuck you, coglione', { lang: ['en', 'it'] });
// true
`
#### Parameters
- str _(string)_ – The input string to scan.
- options _(optional)_ – An object with:
- lang _(string | string[])_: One or more language codes (e.g., 'en', 'it', or ['en', 'it']). If omitted, all supported languages will be used.
- rigidMode _(boolean)_: If true, performs substring detection (e.g., matches "fuckyou"). Defaults to false.
- processedChunkSize _(number)_: Optional internal chunk size for performance control (default is 100).
- customKeywords _(Set\
#### Returns
A Promise – Resolves to true if profanity is detected, otherwise false.
curse-filter comes with built-in express.js middlewares.
The detectMiddleware middleware analizes the whole req.body object for curse words.
`ts
import express, { Request, Response } from 'express';
import { detectMiddleware } from 'curse-filter';
import { registerUserToDB } from './db';
const app = express();
app.use(express.json());
app.post('/register', detectMiddleware, async (req: Request, res: Response) => {
/* If the request body contains curse words, the middleware will automatically
send a 422 response with a message containing the detected curse words.
If no curse words are detected, the middleware will call the next() function. */
await registerUserToDB(req.body);
res.status(200).json({ message: 'User registered!' });
});
`
It is possible to configure the middleware with the following options:
`ts
// Class for configuring the middleware
import { MiddlewaresConfig } from 'curse-filter';
// Default values:
MiddlewareConfig.onError = null; // Called when a curse word is detected, before sending the response
MiddlewareConfig.detectOptions = {
lang: 'en', // Language(s) to use for detection
rigidMode: false, // If true, performs substring detection (e.g., matches "fuckyou")
processedChunkSize: 100, // Optional internal chunk size for performance control
customKeywords: new Set() // A Set to add custom words to look for in the string
}; // Options for the detect function
MiddlewareConfig.errorMessage = 'Not allowed content detected.'; // Message sent in the response
MiddlewareConfig.statusCode = 422; // Status code sent in the response
`
`typescript
import { SupportedLang } from 'curse-filter';
const lang: SupportedLang = 'en';
`
This version drops the CustomKeywords Set-like object to introduce a quicker way of adding custom words to look for and drops support for the synchronous versions of the functions, in favor of promise-based functions. This means that the filter() and detect() functions and the detectMiddleware` middleware are now only asynchronous and return a promise for increased performance.
Made with 💜 by alessandrofoglia07