Add numeric type (#17)

Author: thekevinbrown

index.d.ts

@@ -20,14 +20,17 @@ interface TypeOption {
 	cryptoRandomString({length: 10});
 	//=> '87fc70e2b9'
 
-	cryptoRandomString({length: 10, type:'base64'});
+	cryptoRandomString({length: 10, type: 'base64'});
 	//=> 'mhsX7xmIv/'
 
-	cryptoRandomString({length: 10, type:'url-safe'});
+	cryptoRandomString({length: 10, type: 'url-safe'});
 	//=> 'VEjfNW3Yej'
+
+	cryptoRandomString({length: 10, type: 'numeric'});
+	//=> '8314659141'
 	```
 	*/
-	type?: 'hex' | 'base64' | 'url-safe';
+	type?: 'hex' | 'base64' | 'url-safe' | 'numeric';
 }
 
 interface CharactersOption {
@@ -41,7 +44,7 @@ interface CharactersOption {
 
 	@example
 	```
-	cryptoRandomString({length: 10, characters:'0123456789'});
+	cryptoRandomString({length: 10, characters: '0123456789'});
 	//=> '8796225811'
 	```
 	*/

index.js

@@ -2,6 +2,7 @@
 const crypto = require('crypto');
 
 const urlSafeCharacters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._~'.split('');
+const numericCharacters = '0123456789'.split('');
 
 const generateForCustomCharacters = (length, characters) => {
 	// Generating entropy is faster than complex math operations, so we use the simplest way
@@ -34,7 +35,8 @@ const allowedTypes = [
 	undefined,
 	'hex',
 	'base64',
-	'url-safe'
+	'url-safe',
+	'numeric'
 ];
 
 module.exports = ({length, type, characters}) => {
@@ -70,6 +72,10 @@ module.exports = ({length, type, characters}) => {
 		return generateForCustomCharacters(length, urlSafeCharacters);
 	}
 
+	if (type === 'numeric') {
+		return generateForCustomCharacters(length, numericCharacters);
+	}
+
 	if (characters.length === 0) {
 		throw new TypeError('Expected `characters` string length to be greater than or equal to 1');
 	}

index.test-d.ts

@@ -3,7 +3,10 @@ import cryptoRandomString = require('.');
 
 expectType<string>(cryptoRandomString({length: 10}));
 expectType<string>(cryptoRandomString({length: 10, type: 'url-safe'}));
+expectType<string>(cryptoRandomString({length: 10, type: 'numeric'}));
 expectType<string>(cryptoRandomString({length: 10, characters: '1234'}));
 
 expectError(cryptoRandomString({type: 'url-safe'}));
 expectError(cryptoRandomString({length: 10, type: 'url-safe', characters: '1234'}));
+expectError(cryptoRandomString({type: 'numeric'}));
+expectError(cryptoRandomString({length: 10, type: 'numeric', characters: '1234'}));

readme.md

@@ -26,8 +26,11 @@ cryptoRandomString({length: 10, type: 'base64'});
 cryptoRandomString({length: 10, type: 'url-safe'});
 //=> 'YN-tqc8pOw'
 
-cryptoRandomString({length: 10, characters: '1234567890'});
-//=> '1791935639'
+cryptoRandomString({length: 10, type: 'numeric'});
+//=> '8314659141'
+
+cryptoRandomString({length: 10, characters: 'abc'});
+//=> 'abaaccabac'
 ```
 
 
@@ -52,7 +55,7 @@ Length of the returned string.
 
 Type: `string`<br>
 Default: `'hex'`<br>
-Values: `'hex'` `'base64'` `'url-safe'`
+Values: `'hex'` `'base64'` `'url-safe'` `'numeric'`
 
 Use only characters from a predefined set of allowed characters.
 

test.js

@@ -1,7 +1,7 @@
 import test from 'ava';
 import cryptoRandomString from '.';
 
-// Probailistic, result is always less than or equal to actual set size, chance it is less is below 1e-256 for sizes up to 32656
+// Probabilistic, result is always less than or equal to actual set size, chance it is less is below 1e-256 for sizes up to 32656
 const generatedCharacterSetSize = (options, targetSize) => {
 	const set = new Set();
 	const length = targetSize * 640;
@@ -46,6 +46,14 @@ test('url-safe', t => {
 	t.is(generatedCharacterSetSize({type: 'url-safe'}, 66), 66);
 });
 
+test('numeric', t => {
+	t.is(cryptoRandomString({length: 0, type: 'numeric'}).length, 0);
+	t.is(cryptoRandomString({length: 10, type: 'numeric'}).length, 10);
+	t.is(cryptoRandomString({length: 100, type: 'numeric'}).length, 100);
+	t.regex(cryptoRandomString({length: 100, type: 'numeric'}), /^[\d]*$/); // Sanity check, probabilistic
+	t.is(generatedCharacterSetSize({type: 'numeric'}, 10), 10);
+});
+
 test('characters', t => {
 	t.is(cryptoRandomString({length: 0, characters: '1234'}).length, 0);
 	t.is(cryptoRandomString({length: 10, characters: '1234'}).length, 10);