Nodejs generate short unique alphanumeric

Question

I would like to generate a short unique alphanumeric value to be used as confirmation codes for online purchases. I\'ve looking into https://github.com/broofa/node-uuid but the

Answer 1

A little late on this one but it seems like hashids would work pretty well for this scenario.

https://github.com/ivanakimov/hashids.node.js

hashids (Hash ID's) creates short, unique, decryptable hashes from unsigned integers

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

var hash = hashids.encrypt(12345);
// hash is now 'ryBo'

var numbers = hashids.decrypt('ryBo');
// numbers is now [ 12345 ]

If you want to target ~ 8 characters you could do, the following that calls for a minimum of 8 chars.

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

then this:

hash = hashids.encrypt(1);
// hash is now 'b9iLXiAa'

The accepted answer would be predictable/guessable, this solution should be unique and unpredictable.