A useful type GUID class definition.

guid.ts

const GUID_EMPTY: string = '00000000-0000-0000-0000-000000000000';
const GUID_FORMAT: RegExp = /\{?([a-z0-9]{8}(?:-[a-z0-9]{4}){3}-[a-z0-9]{12})\}?/i;

/**
 * A unique identifier.
 */
export class Guid {

  private _id: string;

  /**
   * Returns an empty GUID.
   */
  static empty(): Guid {
    return new Guid(GUID_EMPTY);
  }

  /**
   * Creates a new GUID.
   */
  static newGuid(): Guid {
    return new Guid(`${Guid.s4()}${Guid.s4()}-${Guid.s4()}-${Guid.s4()}-${Guid.s4()}-${Guid.s4()}${Guid.s4()}${Guid.s4()}`);
  }

  private static s4(): string {
    return Math
      .floor((1 + Math.random()) * 0x10000)
      .toString(16)
      .substring(1);
  }

  /**
   * Creates a new GUID from a string or clones existing guid.
   */
  constructor(id: string | Guid) {

    if (id instanceof Guid) {
      this._id = id.valueOf();
      return;
    }

    if (GUID_FORMAT.test(id)) {
      this._id = GUID_FORMAT.exec(id.toLowerCase())[1];
      return;
    }

    throw new Error(`Invalid GUID ${id}`);
  }

  /**
   * Compares if two GUID's are equal.
   */
  equals(value: string | Guid): boolean {
    try {
      return this._id === (new Guid(value)).valueOf();
    }
    catch (err) {
      return false;
    }
  }

  /**
   * Converts the GUID to a formatted string.
   *
   * Formats:
   *   n = 00000000000000000000000000000000
   *   d = 00000000-0000-0000-0000-000000000000 (default)
   *   b = {00000000-0000-0000-0000-000000000000}
   */
  toString(format: string = 'd'): string {
    switch (format.toLowerCase()) {
      case 'n':
        return this._id.replace('-', '');
      case 'b':
        return `{${this._id}}`;
      default:
        return this._id;
    }
  };

  /**
   * Returns the underlying value.
   */
  valueOf(): string {
    return this._id;
  };
}