[ADDED] min/max and operator options to the exports.mathExpr, extended d tests and (english) readme

.gitignore

@@ -1 +1,3 @@
 /node_modules
+
+\.idea/

.npmignore

@@ -0,0 +1,2 @@
+.git
+test

README.md

@@ -1,119 +1,123 @@
-![svg-captcha](media/header.png)
-
-<div align="center">
-
-[![Build Status](https://img.shields.io/travis/lemonce/svg-captcha/master.svg?style=flat-square)](https://travis-ci.org/lemonce/svg-captcha)
-[![NPM Version](https://img.shields.io/npm/v/svg-captcha.svg?style=flat-square)](https://www.npmjs.com/package/svg-captcha)
-[![NPM Downloads](https://img.shields.io/npm/dm/svg-captcha.svg?style=flat-square)](https://www.npmjs.com/package/svg-captcha)
-
-</div>
-
-> generate svg captcha in node.js
-
-## Translations
-[中文](README_CN.md)
-
-## 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
-```Javascript
-var svgCaptcha = require('svg-captcha');
-
-var captcha = svgCaptcha.create();
-console.log(captcha);
-// {data: '<svg.../svg>', text: 'abcd'}
-```
-with express
-```Javascript
-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 string  
-* `ignoreChars`: '0o1i' // filter out some characters like 0o1i  
-* `noise`: 1 // number of noise lines  
-* `color`: true // characters will have distinct colors instead of grey, true if background option is set  
-* `background`: '#cc9966' // background color of the svg image  
-
-This function returns an object that has the following property:
-* `data`: string // svg path data
-* `text`: 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 captcha
-* `height`: number // height of captcha
-* `fontSize`: number // captcha text size
-* `charPreset`: 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:
-
-![image](media/example.png)
-
-math expression image with color options:
-
-![image2](media/example-2.png)
-
-## 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
-'&lt;text&gt;1234&lt;/text&gt;'.  
-You get
-'&lt;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](LICENSE.md)
+![svg-captcha](media/header.png)
+
+<div align="center">
+
+[![Build Status](https://img.shields.io/travis/lemonce/svg-captcha/master.svg?style=flat-square)](https://travis-ci.org/lemonce/svg-captcha)
+[![NPM Version](https://img.shields.io/npm/v/svg-captcha.svg?style=flat-square)](https://www.npmjs.com/package/svg-captcha)
+[![NPM Downloads](https://img.shields.io/npm/dm/svg-captcha.svg?style=flat-square)](https://www.npmjs.com/package/svg-captcha)
+
+</div>
+
+> generate svg captcha in node.js
+
+## Translations
+[中文](README_CN.md)
+
+## 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
+```Javascript
+var svgCaptcha = require('svg-captcha');
+
+var captcha = svgCaptcha.create();
+console.log(captcha);
+// {data: '<svg.../svg>', text: 'abcd'}
+```
+with express
+```Javascript
+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 string  
+* `ignoreChars`: '0o1i' // filter out some characters like 0o1i  
+* `noise`: 1 // number of noise lines  
+* `color`: true // characters will have distinct colors instead of grey, true if background option is set  
+* `background`: '#cc9966' // background color of the svg image  
+
+This function returns an object that has the following property:
+* `data`: string // svg path data
+* `text`: string // captcha text
+
+#### `svgCaptcha.createMathExpr(options)`  
+Similar to create api, you have the above options plus 3 additional:
+* `mathMin`: 1 // the minimum value the math expression can be
+* `mathMax`: 9 // the maximum value the math expression can be
+* `mathOperator`: + // The operator to use, `+`, `-` or `+-` (for random `+` or `-`)
+
+This function returns an object that has the following property:
+* `data`: string // svg of the math expression
+* `text`: string // the answer of the math expression
+
+#### `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 captcha
+* `height`: number // height of captcha
+* `fontSize`: number // captcha text size
+* `charPreset`: 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:
+
+![image](media/example.png)
+
+math expression image with color options:
+
+![image2](media/example-2.png)
+
+## 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
+'&lt;text&gt;1234&lt;/text&gt;'.  
+You get
+'&lt;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](LICENSE.md)

index.d.ts

@@ -51,6 +51,22 @@ declare class ConfigObject {
 	 * background color of svg image
 	 */
 	background?: string;
+	/**
+	 * default: +
+	 * the math operator to use, "+", "-" or "+/-"
+	 * if unknown operator passed defaults to "+/-"
+	 */
+	mathOperator?: string;
+	/**
+	 * default: 1
+	 * min value of the math expression
+	 */
+	mathMin?: number;
+	/**
+	 * default: 9
+	 * max value of the math expression
+	 */
+	mathMax?: number;
 }
 /**
  * result of captcha generation

lib/index.js

@@ -76,7 +76,7 @@ const create = function (options) {
 };
 
 const createMathExpr = function (options) {
-	const expr = random.mathExpr();
+	const expr = random.mathExpr(options.mathMin, options.mathMax, options.mathOperator);
 	const text = expr.text;
 	const data = createCaptcha(expr.equation, options);
 

lib/random.js

@@ -44,17 +44,39 @@ exports.captchaText = function (options) {
 	return out;
 };
 
+const mathExprPlus = function(leftNumber, rightNumber){
+	const text = (leftNumber + rightNumber).toString();
+	const equation = leftNumber + '+' + rightNumber;
+	return {text, equation}
+}
+
+const mathExprMinus = function(leftNumber, rightNumber){
+	const text = (leftNumber - rightNumber).toString();
+	const equation = leftNumber + '-' + rightNumber;
+	return {text, equation}
+}
+
 /**
- * Returns an object that has the following props:
- * text, equation
+ * Creates a simple math expression using either the + or - operator
+ * @param {number} [min] - The min value of the math expression defaults to 1
+ * @param {number} [max] - The max value of the math expression defaults to 9
+ * @param {string} [operator] - The operator(s) to use
+ * @returns {{equation: string, text: string}}
  */
-exports.mathExpr = function () {
-	const left = randomInt(1, 9);
-	const right = randomInt(1, 9);
-	const text = (left + right).toString();
-	const equation = left + '+' + right;
-
-	return {text, equation};
+exports.mathExpr = function (min, max, operator) {
+	min = min || 1;
+	max = max || 9;
+	operator = operator || '+';
+	const left = randomInt(min, max);
+	const right = randomInt(min, max);
+	switch(operator){
+		case '+':
+			return mathExprPlus(left, right)
+		case '-':
+			return mathExprMinus(left, right)
+		default:
+			return (randomInt(1, 2) % 2) ? mathExprPlus(left, right) : mathExprMinus(left, right);
+	}
 };
 
 // https://github.com/jquery/jquery-color/blob/master/jquery.color.js#L432