生成随机id

  /**
   * 生成随机id
   * @param {*} length
   * @param {*} chars
   */
  function getUUID(length, chars) {
    chars = chars || '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
    length = length || 8
    var result = ''
    for (var i = length; i > 0; --i)
      result += chars[Math.floor(Math.random() * chars.length)]
    return result
  }
  console.log(getUUID(10));//bHrPFSXjDU