genUID from basis.js

 /**
  * Generates unique id (mix datetime and random).
  * @param {number=} len Required length of id (16 by default).
  * @returns {string} Generated id.
  */
  function genUID(len){
    function base36(val){
      return Math.round(val).toString(36);
    }

    // uid should starts with alpha
    var result = base36(10 + 25 * Math.random());

    if (!len)
      len = 16;

    while (result.length < len)
      result += base36(new Date * Math.random());

    return result.substr(0, len);
  }