export abstract class StringHelper {
  static random(len: number, charSet?: string): string {
    charSet = charSet || "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    var randomString = "";
    for (var i = 0; i < len; i++) {
      var randomPoz = Math.floor(Math.random() * charSet.length);
      randomString += charSet.substring(randomPoz, randomPoz + 1);
    }
    return randomString;
  }
}