als-captcha
Advanced tools
als-captcha is a Node.js library for generating and validating a simple yet effective captcha. It employs a combination of image recognition with noise and tilt, basic math problem solving, and several other strategies to differentiate between human users and bots.
To install als-captcha, use npm:
npm i als-captcha
const Captcha = require('als-captcha');
const captcha = new Captcha() // dafult params and eng language for audio
// create captcha
app.get('/captcha', async (req, res) => {
const captchaHtml = await captcha.create(req,res,true) // last parameter include audio
res.send(`<!DOCTYPE html>
<html lang="en">
<head>
<title>HEllo</title>
</head>
<body>
<form>
${captchaHtml}
</form>
<body>
</html>
`);
});
// validate captcha
app.post('/submit-captcha', (req, res) => {
if (catpcha.valid(req)) res.send("right");
else res.send("wrong");
});
als-captcha uses multiple strategies to enhance security:
importantInfo Field: Remains empty and is used to detect bots that might fill it.onchange Event: If the onchange event does not trigger, the bot field retains its default value, indicating a bot.Configuration includes 3 parts:
params(Object) - the parameters for captcha class
lang(String) - the language for audio
'eng', available: eng,ru,hecookieOptions (Object) - options for cookie
prefix (String): Optional. A prefix for cookie names with encrypted values. Default is 's:'.cryptOptions (Object): Optional. An object for initiating encryption.
The parameters includes:
logger(Function): function for logging errors. Default console.logmaxAge (Number): captcha life time (after this time, captcha outdated). Default is 10 minutesfilePath (String): The place for saving captcha tokens start. Default join(__dirname, 'captcha-start')Example for custom cofiguration:
const logs = []
const captcha = new Captcha({
logger:(...e) => logs.push(e),
maxAge:1000*60*30,
filePath:'./captcha-start'
})
langThe Captcha class using als-math-audio-composer for composing audio for captcha.
By default the language is english (eng).
At the moment, available languages are:
eng - englishru - russianhe - hebrewals-math-audio-composer using sync method to read the files and than caching it.
You can cache all needed sounds on init like this:
const captcha = new Captcha({},'ru') // Set Russian as the captcha language
captcha.audioComposer.cacheAll() // Optionally pre-cache all audio files for faster response
The Captcha using crypted cookies for storing token and captcha result. By default cookies sent with the folowing options:
{
path: '/',
secure: true,
httpOnly: true,
maxAge:60*10,
sameSite:'lax'
}
The configuraton builded with als-cookie-options and you can change it.
Here is the example how to change:
const captcha = new Captcha()
captcha.cookieOptions.sameSite = 'strict'
FAQs
Advanced CAPTCHA library
The npm package als-captcha receives a total of 2 weekly downloads. As such, als-captcha popularity was classified as not popular.
We found that als-captcha demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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