diff --git a/tests/ts/JavaScriptUnionVectorTest.js b/tests/ts/JavaScriptUnionVectorTest.js
new file mode 100644
index 0000000..18857d6
--- /dev/null
+++ b/tests/ts/JavaScriptUnionVectorTest.js
@@ -0,0 +1,111 @@
+import assert from 'assert'
+import * as flatbuffers from 'flatbuffers'
+
+import { Character } from './union_vector/character.js'
+import { BookReader, BookReaderT } from './union_vector/book-reader.js'
+import { Attacker, AttackerT } from './union_vector/attacker.js'
+import { Movie, MovieT } from './union_vector/movie.js'
+
+var charTypes = [
+  Character.Belle,
+  Character.MuLan,
+  Character.BookFan,
+  Character.Other
+];
+
+function testMovieBuf(movie) {
+  assert.strictEqual(movie.charactersTypeLength(), charTypes.length);
+  assert.strictEqual(movie.charactersLength(), movie.charactersTypeLength());
+
+  for (var i = 0; i < charTypes.length; ++i) {
+    assert.strictEqual(movie.charactersType(i), charTypes[i]);
+  }
+
+  var bookReader7 = movie.characters(0, new BookReader());
+  assert.strictEqual(bookReader7.booksRead(), 7);
+
+  var attacker = movie.characters(1, new Attacker());
+  assert.strictEqual(attacker.swordAttackDamage(), 5);
+
+  var bookReader2 = movie.characters(2, new BookReader());
+  assert.strictEqual(bookReader2.booksRead(), 2);
+
+  var other = movie.characters(3, '');
+  assert.strictEqual(other, "I am other");
+}
+
+function testMovieUnpack(movie) {
+  assert.strictEqual(movie.charactersType.length, charTypes.length);
+  assert.strictEqual(movie.characters.length, movie.charactersType.length);
+
+  for (var i = 0; i < charTypes.length; ++i) {
+    assert.strictEqual(movie.charactersType[i], charTypes[i]);
+  }
+
+  var bookReader7 = movie.characters[0];
+  assert.strictEqual(bookReader7 instanceof BookReaderT, true);
+  assert.strictEqual(bookReader7.booksRead, 7);
+
+  var attacker = movie.characters[1];
+  assert.strictEqual(attacker instanceof AttackerT, true);
+  assert.strictEqual(attacker.swordAttackDamage, 5);
+
+  var bookReader2 = movie.characters[2];
+  assert.strictEqual(bookReader2 instanceof BookReaderT, true);
+  assert.strictEqual(bookReader2.booksRead, 2);
+
+  var other = movie.characters[3];
+  assert.strictEqual(other, "I am other");
+}
+
+function createMovie(fbb) {
+  Attacker.startAttacker(fbb);
+  Attacker.addSwordAttackDamage(fbb, 5);
+  var attackerOffset = Attacker.endAttacker(fbb);
+
+  var charTypesOffset = Movie.createCharactersTypeVector(fbb, charTypes);
+  var charsOffset = 0;
+
+  let otherOffset = fbb.createString("I am other");
+
+  charsOffset = Movie.createCharactersVector(
+    fbb,
+    [
+      BookReader.createBookReader(fbb, 7),
+      attackerOffset,
+      BookReader.createBookReader(fbb, 2),
+      otherOffset
+    ]
+  );
+
+  Movie.startMovie(fbb);
+  Movie.addCharactersType(fbb, charTypesOffset);
+  Movie.addCharacters(fbb, charsOffset);
+  Movie.finishMovieBuffer(fbb, Movie.endMovie(fbb))
+}
+
+function main() {
+  var fbb = new flatbuffers.Builder();
+
+  createMovie(fbb);
+
+  var buf = new flatbuffers.ByteBuffer(fbb.asUint8Array());
+
+  var movie = Movie.getRootAsMovie(buf);
+  testMovieBuf(movie);
+
+  testMovieUnpack(movie.unpack());
+
+  var movie_to = new MovieT();
+  movie.unpackTo(movie_to);
+  testMovieUnpack(movie_to);
+
+  fbb.clear();
+  Movie.finishMovieBuffer(fbb, movie_to.pack(fbb));
+  var unpackBuf = new flatbuffers.ByteBuffer(fbb.asUint8Array());
+  testMovieBuf(Movie.getRootAsMovie(unpackBuf));
+  
+  console.log('FlatBuffers union vector test: completed successfully');
+}
+
+main();