shortid-extend/lib/build.js

Alternative versión with options from Dylan Greene ShortId

'use strict';

var generate = require('./generate');
var alphabet = require('./alphabet');

// Ignore all milliseconds before a certain time to reduce the size of the date entropy without sacrificing uniqueness.
// This number should be updated every year or so to keep the generated id short.
// To regenerate `new Date() - 0` and bump the version. Always bump the version!
var REDUCE_TIME = 1459707606518;

// don't change unless we change the algos or REDUCE_TIME
// must be an integer and less than 16
var version = 6;

// Counter is used when shortid is called multiple times in one second.
var counter;

// Remember the last time shortid was called in case counter is needed.
var previousSeconds;

// Default Length;

var _defaultLength = true;
var _configLength;

function setDefaults(config) {
    if(config.disableDefault) {
        _defaultLength = false;
        _configLength = config.configLength
    }
}

/**
 * Generate unique id
 * Returns string id
 */
function build(clusterWorkerId) {
    var str = '';
    if(_defaultLength) {
        var seconds = Math.floor((Date.now() - REDUCE_TIME) * 0.001);
        if (seconds === previousSeconds) {
            counter++;
        } else {
            counter = 0;
            previousSeconds = seconds;
        }

        str = str + generate(version);
        str = str + generate(clusterWorkerId);
        if (counter > 0) {
            str = str + generate(counter);
        }
        str = str + generate(seconds);
        return str;
    } else {
        for(var i = 0; i < _configLength; i++){
            str = str + generate(version);
        }
        return str
    }
}

module.exports = {
    build: build,
    setDefaults: setDefaults
};