Awesome
generate svg captcha in node.js
Translations
useful if you
- cannot or do not want to use google recaptcha
- have issue with install c++ addon
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.
size
: 4 // size of random stringignoreChars
: '0o1i' // filter out some characters like 0o1inoise
: 1 // number of noise linescolor
: true // characters will have distinct colors instead of grey, true if background option is setbackground
: '#cc9966' // background color of the svg image
This function returns an object that has the following property:
data
: string // svg path datatext
: string // captcha text
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.
url
: string // path to your font This api is a wrapper around loadFont api of opentype.js.
Your may need experiment around various options to make your own font accessible.
See the following api.
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:
width
: number // width of captchaheight
: number // height of captchafontSize
: number // captcha text sizecharPreset
: string // random character preset
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:
math expression image with color options:
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