1. module rand-token
   1. function rand-token.generate (size, chars)
   2. function rand-token.generator (options)
   3. function rand-token.suid (length, epoch, prefixLength)
   4. function rand-token.uid (size, chars)

module rand-token

function rand-token.generate (size, chars)

• description and source-code

  generate = function (size, chars) {
    if( chars ) {
      validateTokenChars(chars);
    } else {
      chars = options.chars;
    }
    var max = Math.floor(256 / chars.length) * chars.length;
    var ret = "";
    while( ret.length < size ) {
      var buf = options.source(size - ret.length);
      for(var i=0;i<buf.length;i++) {
        var x = buf.readUInt8(i);
        if( x < max ) {
          ret += chars[x % chars.length];
        }
      }
    }
    return ret;
  }

• example usage

  ...
  
  # Usage
  
  // Create a token generator with the default settings:
  var randtoken = require('rand-token');
  
  // Generate a 16 character alpha-numeric token:
  var token = randtoken.generate(16);
  
  // Use it as a replacement for uid:
  var uid = require('rand-token').uid;
  var token = uid(16);
  
  // Generate mostly sequential tokens:
  var suid = require('rand-token').suid;
  ...

function rand-token.generator (options)

• description and source-code

  function buildGenerator(options) {
    assert(!options || typeof(options) == 'object');
    options = options || {};
    options.chars = options.chars || defaults.chars;
    options.source = options.source || defaults.source;
  
    // Allowed characters
    switch( options.chars ) {
      case 'default':
        options.chars = alphaNumeric;
        break;
      case 'a-z':
      case 'alpha':
        options.chars = alphaLower;
        break;
      case 'A-Z':
      case 'ALPHA':
        options.chars = alphaUpper;
        break;
      case '0-9':
      case 'numeric':
        options.chars = numeric;
        break;
      case 'base32':
        options.chars = alphaUpper + "234567";
        break;
      default:
        // use the characters as is
    }
    validateTokenChars(options.chars);
  
    // Source of randomness:
    switch( options.source ) {
      case 'default':
        options.source = function(size, cb) {
          return cryptoRandomBytes(size, !cb ? null : function (buf){
            return cb(null, buf);
          });
        };
        break;
      case 'crypto':
        options.source = crypto.randomBytes;
        break;
      case 'math':
        options.source = function(size, cb) {
          var buf = new Buffer(size);
          for(var i=0;i<size;i++) {
            buf.writeUInt8(Math.floor(256 * Math.random()), i);
          }
          if( cb ) {
            cb(null, buf);
          } else {
            return buf;
          }
        };
        break;
      default:
        assert(typeof(options.source) == 'function');
    }
  
    return {
      "generate": function(size, chars) {
        if( chars ) {
          validateTokenChars(chars);
        } else {
          chars = options.chars;
        }
        var max = Math.floor(256 / chars.length) * chars.length;
        var ret = "";
        while( ret.length < size ) {
          var buf = options.source(size - ret.length);
          for(var i=0;i<buf.length;i++) {
            var x = buf.readUInt8(i);
            if( x < max ) {
              ret += chars[x % chars.length];
            }
          }
        }
        return ret;
      }
    };
  }

• example usage

  ...
  
      // Generate a 24 (16 + 8) character alpha-numeric token:
      var token = suid(16)
  
  To generate only lower case letters (a-z):
  
      // Create a token generator with the default settings:
      var randtoken = require('rand-token').generator({
        chars: 'a-z'
      });
  
      // Generate a 16 character token:
      var token = randtoken.generate(16);
  
  Alternatively, you can create a generator with the default options and pass the characters to use as the second parameter to `generate
  `:
  ...

function rand-token.suid (length, epoch, prefixLength)

• description and source-code

  suid = function (length, epoch, prefixLength) {
    epoch = epoch || defaultEpoch;
    prefixLength = prefixLength || defaultPrefixLength;
    return suidPrefix(epoch, prefixLength) + defaultGenerator.generate(length);
  }

• example usage

  n/a

function rand-token.uid (size, chars)

• description and source-code

  uid = function (size, chars) {
    if( chars ) {
      validateTokenChars(chars);
    } else {
      chars = options.chars;
    }
    var max = Math.floor(256 / chars.length) * chars.length;
    var ret = "";
    while( ret.length < size ) {
      var buf = options.source(size - ret.length);
      for(var i=0;i<buf.length;i++) {
        var x = buf.readUInt8(i);
        if( x < max ) {
          ret += chars[x % chars.length];
        }
      }
    }
    return ret;
  }

• example usage

  n/a