hashids

Hashids

A small Node.js class to generate YouTube-like ids from one or many numbers. Use hashids when you do not want to expose your database ids to the user. Read full documentation at: http://hashids.org/node-js

Installation

1. Node it up: http://nodejs.org/download/

2. Install using npm:

   npm install hashids

Updating from v0.3 to 1.0?

Read the CHANGELOG at the bottom of this readme!

Client-side Version

If you're looking for a client-side Bower version, there's a separate repo: https://github.com/ivanakimov/hashids.js/

Production Note

BE CAREFUL WHICH VERSION OF HASHIDS YOU ARE USING.

Since future improvements to Hashids might alter produced hashes, it's a good idea to specify exact Hashids version in your package.json, if their consistency is important to you (if you are storing them in database):

	
	"dependencies": {
		"hashids": "1.0.1"
	}

Usage

Encoding one number

You can pass a unique salt value so your ids differ from everyone else's. I use "this is my salt" as an example.

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt");

var id = hashids.encode(12345);

id is now going to be:

NkK9

Decoding

Notice during decoding, same salt value is used:

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt");

var numbers = hashids.decode("NkK9");

numbers is now going to be:

[ 12345 ]

Decoding with different salt

Decoding will not work if salt is changed:

var Hashids = require("hashids"),
	hashids = new Hashids("this is my pepper");

var numbers = hashids.decode("NkK9");

numbers is now going to be:

[]

Encoding several numbers

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt");

var id = hashids.encode(683, 94108, 123, 5);

id is now going to be:

aBMswoO2UB3Sj

You can also pass an array:

var arr = [683, 94108, 123, 5];
var id = hashids.encode(arr);

Decoding is done the same way

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt");

var numbers = hashids.decode("aBMswoO2UB3Sj");

numbers is now going to be:

[ 683, 94108, 123, 5 ]

Encoding and specifying minimum id length

Here we encode integer 1, and set the minimum id length to 8 (by default it's 0 -- meaning ids will be the shortest possible length).

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt", 8);

var id = hashids.encode(1);

id is now going to be:

gB0NV05e

Decoding

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt", 8);

var numbers = hashids.decode("gB0NV05e");

numbers is now going to be:

[ 1 ]

Specifying custom id alphabet

Here we set the alphabet to consist of valid hex characters: "0123456789abcdef"

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt", 0, "0123456789abcdef");

var id = hashids.encode(1234567);

id is now going to be:

b332db5

MongoDB Support

MongoDB uses hex strings for their ObjectIds. You can convert them to Hashids like this:

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt");

var id = hashids.encodeHex("507f191e810c19729de860ea");
var objectId = hashids.decodeHex(id);

id will be:

yNyaoWeKWVINWqvaM9bw

objectId will be as expected:

507f191e810c19729de860ea

The length of the hex string does not matter -- it does not have to be a MongoDB ObjectId.

Randomness

The primary purpose of hashids is to obfuscate ids. It's not meant or tested to be used for security purposes or compression. Having said that, this algorithm does try to make these hashes unguessable and unpredictable:

Repeating numbers

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt");

var id = hashids.encode(5, 5, 5, 5);

You don't see any repeating patterns that might show there's 4 identical numbers in the id:

1Wc8cwcE

Same with incremented numbers:

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt");

var id = hashids.encode(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

id will be :

kRHnurhptKcjIDTWC3sx

Incrementing number ids:

var Hashids = require("hashids"),
	hashids = new Hashids("this is my salt");

var id1 = hashids.encode(1), /* NV */
	id2 = hashids.encode(2), /* 6m */
	id3 = hashids.encode(3), /* yD */
	id4 = hashids.encode(4), /* 2l */
	id5 = hashids.encode(5); /* rD */

Curses! #$%@

This code was written with the intent of placing created hashes in visible places - like the URL. Which makes it unfortunate if generated hashes accidentally formed a bad word.

Therefore, the algorithm tries to avoid generating most common English curse words. This is done by never placing the following letters next to each other:

c, C, s, S, f, F, h, H, u, U, i, I, t, T

Running tests

Hashids uses jasmine spec tests, particularly jasmine-node.

To install sudo npm install -g jasmine-node then just run jasmine-node . in the root folder.

Contact

Follow me @IvanAkimov

Or http://ivanakimov.com

License

MIT License. See the LICENSE file. You can use Hashids in open source projects and commercial products. Don't break the Internet. Kthxbye.