Zoia Captcha

Zoia Captcha (zoia-captcha) is a library for captcha generation based on JIMP (no external dependenices like ImageMagick or GD are required).

Usage

First, install the latest version of zoia-captcha from NPM:

npm i zoia-captcha --save

Then you need to include zoia-captcha in your code:

const captcha = require('zoia-captcha');

zoia-captcha exports the following methods:

getCaptcha = async (code, backgroundChars = backgroundCharsDefault, backgroundColor = backgroudColorDefault)

• The mandatory parameter is code which represents a string which is displayed on the image
• The first optional parameter is backgroundChars (default value is [...'0123456789']) which indicates which characters are displayed on the background as "garbage"
• The second optional parameter is backgroundColor (default value is 0xFFFFFFFF) which indicates the background color of the captcha image (it's not recommended to set the opacity to 00 as it makes easier to recognize the captcha image)

The method getCaptcha returns a promise and resolves a binary image buffer.

Examples

To save the result image to a file, you may use the following code:

const zcaptcha = require('zoia-captcha');
const fs = require('fs');
const test = async() => {
    const img = await zcaptcha.getCaptcha('1234');
    fs.writeFileSync('image.png', img);
};
test();

In the following example there is a 4-digit captcha is returned as an Express route:

const getCaptcha = async (req, res) => {
    const code = Math.random().toString().substr(2, 4);
    const image = await captcha.getCaptcha(code);
    res.writeHead(200, {
        'Content-Type': 'image/png'
    });
    return res.end(image, 'binary');
};