feat: support .net byte order (#124) (#9)

src/Guid.ts

@@ -191,7 +191,7 @@ export class Guid {
 
  /**
  * Returns true if this {@link Guid} is equals to {@link Guid.EMPTY}.
- * @returns boolean
+ * @returns {boolean}
  */
  @enumerable(true)
  public isEmpty(): boolean {
@@ -200,14 +200,17 @@ export class Guid {
 
  /**
  * Returns the 16-byte value of this {@link Guid}.
+ * @param toLittleEndian (optional) signals that the bytes should encode the
+ * first three fields of this {@link Guid} as little-endian numbers. Defaults
+ * to {@link Guid.useLittleEndianBytes}.
  * @returns {number[]}
  */
  @enumerable(true)
- public toByteArray(): number[] {
+ public toByteArray(toLittleEndian = Guid.useLittleEndianBytes): number[] {
  if (!this._bytes) {
  this._bytes = Guid.stringToBytes(
  this._value,
- Guid.isBigEndian(this.variant)
+ !toLittleEndian && Guid.isBigEndian(this.variant)
  );
  }
 
@@ -274,6 +277,15 @@ export class Guid {
  @enumerable(true)
  public static readonly EMPTY: Guid = new Guid(EMPTY_VALUE, EMPTY_BYTES);
 
+ /**
+ * Changes the default behavior of {@link fromByteArray} and {@link toByteArray}
+ * to consume and output byte arrays respectively, containing the first three
+ * fields of the Guid as little-endian numbers. This is useful when reading or
+ * to output .NET-compatible byte array representations.
+ */
+ @enumerable(true)
+ public static useLittleEndianBytes = false;
+
  /**
  * Gets the generator function
  */
@@ -380,17 +392,24 @@ export class Guid {
  /**
  * Creates a new {@link Guid} from a byte array.
  * @param bytes a 16-length array of 8-bit unsigned integers
+ * @param isLittleEndian (optional) signals that the bytes encode the first
+ * three fields of the Guid as little-endian numbers. Defaults to
+ * {@link Guid.useLittleEndianBytes}.
  */
  @enumerable(true)
- public static fromByteArray(bytes: number[]): Guid {
- const result = Guid.checkBytes(bytes);
+ public static fromByteArray(
+ bytes: number[],
+ isLittleEndian = Guid.useLittleEndianBytes
+ ): Guid {
+ const result = Guid.checkBytes(bytes, isLittleEndian);
 
  if (result == null) {
  throw new TypeError("Incorrect bytes received for a GUID!");
  }
 
  const [bts, variant, version] = result;
- const value = Guid.bytesToString(bytes, Guid.isBigEndian(variant));
+ const bigEndian = !isLittleEndian && Guid.isBigEndian(variant);
+ const value = Guid.bytesToString(bytes, bigEndian);
  const guid = new Guid(value, bts);
  guid._variant = variant;
  guid._version = version;
@@ -490,15 +509,16 @@ export class Guid {
  }
 
  if (Array.isArray(value)) {
- return !!Guid.checkBytes(value as number[]);
+ return !!Guid.checkBytes(value as number[], false);
  }
 
  return false;
  }
 
  @enumerable()
  private static checkBytes(
- bytes: number[]
+ bytes: number[],
+ isLittleEndian: boolean
  ): [number[], GuidVariant, GuidVersion] | null {
  if (bytes.length !== BYTE_COUNT) {
  // not the right amount of bytes are in the collection
@@ -522,9 +542,9 @@ export class Guid {
  }
  }
 
- const version = Guid.getVersion(
-  Guid.toNumber(bytes.slice(6, 8), Guid.isBigEndian(variant))
- );
+ const bigEndian = !isLittleEndian && Guid.isBigEndian(variant);
+ const timeHiAndVersion = Guid.toNumber(bytes.slice(6, 8), bigEndian);
+ const version = Guid.getVersion(timeHiAndVersion);
  if (version < 1 || version > 5) {
  // Unknown version
  return null;