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generate svg captcha in node.js

Translations

中文

useful if you

install

npm install --save svg-captcha

usage

var svgCaptcha = require('svg-captcha');

var captcha = svgCaptcha.create();
console.log(captcha);
// {data: '<svg.../svg>', text: 'abcd'}

with express

var svgCaptcha = require('svg-captcha');

app.get('/captcha', function (req, res) {
	var captcha = svgCaptcha.create();
	req.session.captcha = captcha.text;
	
	res.type('svg');
	res.status(200).send(captcha.data);
});

API

svgCaptcha.create(options)

If no option is passed, you will get a random string of four characters and corresponding svg.

This function returns an object that has the following property:

svgCaptcha.createMathExpr(options)

Similar to create api, you have the same options and return value. The difference is that data is a svg will be an math equation on screen and text will be the result of that equation in string, otherwise the usage is the same as above.

svgCaptcha.loadFont(url)

Load your own font and override the default font.

svgCaptcha.options

Gain access to global setting object. It is used for create and createMathExpr api as the default options.

In addition to size, noise, color, and background, you can also set the following property:

svgCaptcha.randomText([size|options])

return a random string.

svgCaptcha(text, options)

return a svg captcha based on text provided.

In pre 1.1.0 version you have to call these two functions,
now you can call create() to save some key strokes ;).

sample image

default captcha image:

image

math expression image with color options:

image2

why use svg?

It does not require any c++ addon.
The result image is smaller than jpeg image.

This has to be a joke. /<text.+>;.+</text>/g.test...

svg captcha uses opentype.js underneath, which means that there is no '<text>1234</text>'.
You get '<path fill="#444" d="M104.83 19.74L107.85 19.74L112 33.56L116.13 19.74L119.15 19.74L113.48 36.85...'
instead.

Even though you can write a program that convert svg to png, svg captcha has done its job
—— make captcha recognition harder

License

MIT