diff --git a/README.md b/README.md
index dd49b35..7260bd5 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,15 @@ uncompressed.
 In deno:
 
 ```typescript
-import { Serializer } from "https://code.thunderk.net/typescript/serializer/raw/branch/master/mod.ts";
+import { Serializer } from "https://js.thunderk.net/serializer/mod.ts";
+```
+
+In browser:
+
+```html
+<script type="module">
+import { Serializer } from "https://js.thunderk.net/serializer/mod.js";
+</script>
 ```
 
 ## Use
diff --git a/TODO.md b/TODO.md
index f321421..49a13f2 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1 +1,3 @@
+# TODO
+
 - Add protocol version, to handle breaking changes
diff --git a/doc/usage.md b/doc/usage.md
index 1c265ca..3a9e9e4 100644
--- a/doc/usage.md
+++ b/doc/usage.md
@@ -3,7 +3,15 @@
 In deno:
 
 ```typescript
-import { Serializer } from "https://code.thunderk.net/typescript/serializer/raw/branch/master/mod.ts";
+import { Serializer } from "https://js.thunderk.net/serializer/mod.ts";
+```
+
+In browser:
+
+```html
+<script type="module">
+import { Serializer } from "https://js.thunderk.net/serializer/mod.js";
+</script>
 ```
 
 ## Use
diff --git a/serializer.test.ts b/serializer.test.ts
index b3ed531..c49efbe 100644
--- a/serializer.test.ts
+++ b/serializer.test.ts
@@ -1,8 +1,9 @@
 import {
+  describe,
   expect,
   it,
   mock,
-} from "https://code.thunderk.net/typescript/devtools/raw/1.2.2/testing.ts";
+} from "https://code.thunderk.net/typescript/devtools/raw/1.3.0/testing.ts";
 import { Serializer } from "./serializer.ts";
 
 class TestSerializerObj1 {
@@ -62,145 +63,152 @@ function checkReversability(
   return loaded;
 }
 
-it("serializes simple objects", () => {
-  var obj = {
-    "a": 5,
-    "b": null,
-    "c": [{ "a": 2 }, "test"],
-    "d": new Set([1, 4]),
-    "e": new Map([["z", 8], ["t", 2]]),
-  };
-  const result = checkReversability(obj);
-  expect(result["a"]).toBe(5);
-  expect(result["b"]).toBe(null);
-  expect(result["c"][0]["a"]).toBe(2);
-  expect(result["d"].has(1)).toBe(true);
-  expect(result["d"].has(2)).toBe(false);
-  expect(result["e"].get("z")).toBe(8);
-  expect(result["e"].get("k")).toBeUndefined();
+describe(Serializer, () => {
+  it("serializes simple objects", () => {
+    var obj = {
+      "a": 5,
+      "b": null,
+      "c": [{ "a": 2 }, "test"],
+      "d": new Set([1, 4]),
+      "e": new Map([["z", 8], ["t", 2]]),
+    };
+    const result = checkReversability(obj);
+    expect(result["a"]).toBe(5);
+    expect(result["b"]).toBe(null);
+    expect(result["c"][0]["a"]).toBe(2);
+    expect(result["d"].has(1)).toBe(true);
+    expect(result["d"].has(2)).toBe(false);
+    expect(result["e"].get("z")).toBe(8);
+    expect(result["e"].get("k")).toBeUndefined();
 
-  checkReversability(new Set(["a", new Set([1, "b"])]));
-  checkReversability(new Map([["a", new Map([[1, "test"]])]]));
-});
-
-it("restores objects constructed from class", () => {
-  let loaded = checkReversability(new TestSerializerObj1(5));
-  expect(loaded.a).toBe(5);
-  expect(loaded).toBeInstanceOf(TestSerializerObj1);
-
-  loaded = checkReversability(new TestSerializerObj1(5), TEST_NS_FLAT);
-  expect(loaded.a).toBe(5);
-  expect(loaded).toBeInstanceOf(TestSerializerObj1);
-
-  loaded = checkReversability(new TestSerializerObj1(5), TEST_NS_RENAME);
-  expect(loaded.a).toBe(5);
-  expect(loaded).toBeInstanceOf(TestSerializerObj1);
-});
-
-it("stores one version of the same object", () => {
-  var a = new TestSerializerObj1(8);
-  var b = new TestSerializerObj1(8);
-  var c = {
-    "r": a,
-    "s": ["test", a],
-    "t": a,
-    "u": b,
-  };
-  var loaded = checkReversability(c);
-  expect(loaded.t).toBe(loaded.r);
-  expect(loaded.s[1]).toBe(loaded.r);
-  expect(loaded.u).not.toBe(loaded.r);
-});
-
-it("handles circular references", () => {
-  var a: any = { b: {} };
-  a.b.c = a;
-
-  checkReversability(a, undefined, (loaded) => {
-    expect(Object.keys(loaded)).toEqual(["b"]);
-    expect(Object.keys(loaded.b)).toEqual(["c"]);
-    expect(Object.keys(loaded.b.c)).toEqual(["b"]);
-    expect(Object.keys(loaded.b.c.b)).toEqual(["c"]);
-    expect(loaded.b.c).toBe(loaded);
-    expect(loaded.b.c.b).toBe(loaded.b);
+    checkReversability(new Set(["a", new Set([1, "b"])]));
+    checkReversability(new Map([["a", new Map([[1, "test"]])]]));
   });
-});
 
-it("ignores some classes", () => {
-  let serializer = new Serializer(TEST_NS);
-  serializer.addIgnoredClass("TestSerializerObj1");
+  it("restores objects constructed from class", () => {
+    let loaded = checkReversability(new TestSerializerObj1(5));
+    expect(loaded.a).toBe(5);
+    expect(loaded).toBeInstanceOf(TestSerializerObj1);
 
-  let data = serializer.serialize({ a: 5, b: new TestSerializerObj1() });
-  let loaded = serializer.unserialize(data);
+    loaded = checkReversability(new TestSerializerObj1(5), TEST_NS_FLAT);
+    expect(loaded.a).toBe(5);
+    expect(loaded).toBeInstanceOf(TestSerializerObj1);
 
-  expect(loaded).toEqual({ a: 5, b: undefined });
+    loaded = checkReversability(new TestSerializerObj1(5), TEST_NS_RENAME);
+    expect(loaded.a).toBe(5);
+    expect(loaded).toBeInstanceOf(TestSerializerObj1);
+  });
 
-  serializer = new Serializer(TEST_NS);
-  serializer.addIgnoredClass(TestSerializerObj1);
+  it("serializes reference to class type", () => {
+    let loaded = checkReversability(TestSerializerObj1);
+    expect(loaded).toBe(TestSerializerObj1);
+  });
 
-  data = serializer.serialize({ a: 5, b: new TestSerializerObj1() });
-  loaded = serializer.unserialize(data);
+  it("stores one version of the same object", () => {
+    var a = new TestSerializerObj1(8);
+    var b = new TestSerializerObj1(8);
+    var c = {
+      "r": a,
+      "s": ["test", a],
+      "t": a,
+      "u": b,
+    };
+    var loaded = checkReversability(c);
+    expect(loaded.t).toBe(loaded.r);
+    expect(loaded.s[1]).toBe(loaded.r);
+    expect(loaded.u).not.toBe(loaded.r);
+  });
 
-  expect(loaded).toEqual({ a: 5, b: undefined });
+  it("handles circular references", () => {
+    var a: any = { b: {} };
+    a.b.c = a;
 
-  serializer = new Serializer(TEST_NS_RENAME);
-  serializer.addIgnoredClass(TestSerializerObj1);
+    checkReversability(a, undefined, (loaded) => {
+      expect(Object.keys(loaded)).toEqual(["b"]);
+      expect(Object.keys(loaded.b)).toEqual(["c"]);
+      expect(Object.keys(loaded.b.c)).toEqual(["b"]);
+      expect(Object.keys(loaded.b.c.b)).toEqual(["c"]);
+      expect(loaded.b.c).toBe(loaded);
+      expect(loaded.b.c.b).toBe(loaded.b);
+    });
+  });
 
-  data = serializer.serialize({ a: 5, b: new TestSerializerObj1() });
-  loaded = serializer.unserialize(data);
-
-  expect(loaded).toEqual({ a: 5, b: undefined });
-});
-
-it("ignores functions", () => {
-  let serializer = new Serializer(TEST_NS);
-  let data = serializer.serialize({ obj: new TestSerializerObj2() });
-  let loaded = serializer.unserialize(data);
-
-  let expected = <any> new TestSerializerObj2();
-  expected.a = undefined;
-  expected.b[0] = undefined;
-  expect(loaded).toEqual({ obj: expected });
-});
-
-it("calls specific postUnserialize", () => {
-  let serializer = new Serializer(TEST_NS);
-  let data = serializer.serialize({ obj: new TestSerializerObj3() });
-  let loaded = serializer.unserialize(data);
-
-  let expected = new TestSerializerObj3();
-  expected.a = [1, 2, 3];
-  expect(loaded).toEqual({ obj: expected });
-});
-
-it("handles missing classes", () => {
-  mock(console, "error", undefined, (mock_error) => {
+  it("ignores some classes", () => {
     let serializer = new Serializer(TEST_NS);
-    let data = serializer.serialize({ obj: new TestSerializerObj4() });
+    serializer.addIgnoredClass("TestSerializerObj1");
+
+    let data = serializer.serialize({ a: 5, b: new TestSerializerObj1() });
     let loaded = serializer.unserialize(data);
-    expect(loaded).toEqual({ obj: { a: 0 } });
-    expect(mock_error).toHaveBeenCalledWith(
-      "Can't find class",
-      "TestSerializerObj4",
-    );
+
+    expect(loaded).toEqual({ a: 5, b: undefined });
+
+    serializer = new Serializer(TEST_NS);
+    serializer.addIgnoredClass(TestSerializerObj1);
+
+    data = serializer.serialize({ a: 5, b: new TestSerializerObj1() });
+    loaded = serializer.unserialize(data);
+
+    expect(loaded).toEqual({ a: 5, b: undefined });
+
+    serializer = new Serializer(TEST_NS_RENAME);
+    serializer.addIgnoredClass(TestSerializerObj1);
+
+    data = serializer.serialize({ a: 5, b: new TestSerializerObj1() });
+    loaded = serializer.unserialize(data);
+
+    expect(loaded).toEqual({ a: 5, b: undefined });
+  });
+
+  it("ignores functions", () => {
+    let serializer = new Serializer(TEST_NS);
+    let data = serializer.serialize({ obj: new TestSerializerObj2() });
+    let loaded = serializer.unserialize(data);
+
+    let expected: any = new TestSerializerObj2();
+    expected.a = undefined;
+    expected.b[0] = undefined;
+    expect(loaded).toEqual({ obj: expected });
+  });
+
+  it("calls specific postUnserialize", () => {
+    let serializer = new Serializer(TEST_NS);
+    let data = serializer.serialize({ obj: new TestSerializerObj3() });
+    let loaded = serializer.unserialize(data);
+
+    let expected = new TestSerializerObj3();
+    expected.a = [1, 2, 3];
+    expect(loaded).toEqual({ obj: expected });
+  });
+
+  it("handles missing classes", () => {
+    mock(console, "error", undefined, (mock_error) => {
+      let serializer = new Serializer(TEST_NS);
+      let data = serializer.serialize({ obj: new TestSerializerObj4() });
+      let loaded = serializer.unserialize(data);
+      expect(loaded).toEqual({ obj: { a: 0 } });
+      expect(mock_error).toHaveBeenCalledWith(
+        "Can't find class",
+        "TestSerializerObj4",
+      );
+    });
+  });
+
+  it("uses namespace alias to protect from property mangling", () => {
+    const data = {
+      a: new TestSerializerObj1(1),
+      b: new TestSerializerObj1(2),
+      c: [new TestSerializerObj1(3)],
+    };
+
+    const serializer1 = new Serializer(TEST_NS);
+    const serializer2 = new Serializer(TEST_NS_RENAME);
+
+    const dumped1 = serializer1.serialize(data);
+    const dumped2 = serializer2.serialize(data);
+
+    expect(dumped1.length).toBeGreaterThan(dumped2.length);
+
+    expect(serializer1.unserialize(dumped1)).toEqual(data);
+    expect(serializer2.unserialize(dumped2)).toEqual(data);
   });
 });
-
-it("uses namespace alias to protect from property mangling", () => {
-  const data = {
-    a: new TestSerializerObj1(1),
-    b: new TestSerializerObj1(2),
-    c: [new TestSerializerObj1(3)],
-  };
-
-  const serializer1 = new Serializer(TEST_NS);
-  const serializer2 = new Serializer(TEST_NS_RENAME);
-
-  const dumped1 = serializer1.serialize(data);
-  const dumped2 = serializer2.serialize(data);
-
-  expect(dumped1.length).toBeGreaterThan(dumped2.length);
-
-  expect(serializer1.unserialize(dumped1)).toEqual(data);
-  expect(serializer2.unserialize(dumped2)).toEqual(data);
-});
diff --git a/serializer.ts b/serializer.ts
index d529e77..fda2cc0 100644
--- a/serializer.ts
+++ b/serializer.ts
@@ -41,18 +41,32 @@ export class Serializer {
     // Collect objects
     var objects: Object[] = [];
     var stats: any = {};
+
+    function add(value: any): void {
+      if (objects.indexOf(value) < 0) {
+        objects.push(value);
+      }
+    }
+
     crawl(obj, (value) => {
       if (isObject(value)) {
         var vtype = classname(value);
         if (vtype != "" && this.ignored.indexOf(vtype) < 0) {
           stats[vtype] = (stats[vtype] || 0) + 1;
-          if (objects.indexOf(value) < 0) {
-            objects.push(value);
-          }
+          add(value);
           return value;
         } else {
           return STOP_CRAWLING;
         }
+      } else if (typeof value == "function") {
+        const found = Object.entries(this.namespace).find(([_, cons]) =>
+          cons === value
+        );
+        if (found && this.ignored.indexOf(found[0]) < 0) {
+          // Keep references to constructors in the namespace
+          add(value);
+        }
+        return STOP_CRAWLING;
       } else {
         return value;
       }
@@ -63,7 +77,8 @@ export class Serializer {
     var fobjects = objects.map((value) => this.encodeObject(value));
     return JSON.stringify(fobjects, (key, value) => {
       if (
-        key != "$f" && isObject(value) && !value.hasOwnProperty("$c") &&
+        key != "$f" && (isObject(value) || typeof value == "function") &&
+        !value.hasOwnProperty("$c") &&
         !value.hasOwnProperty("$i")
       ) {
         return { $i: objects.indexOf(value) };
@@ -132,6 +147,10 @@ export class Serializer {
         $c: ctype,
         $f: Array.from(obj),
       };
+    } else if (typeof obj == "function") {
+      return {
+        $c: obj.name,
+      };
     } else {
       return {
         $c: this.namespace_rev[ctype] || ctype,
@@ -149,8 +168,10 @@ export class Serializer {
       return new Set(objdata.$f);
     } else if (ctype == "Map") {
       return new Map(objdata.$f);
-    } else {
+    } else if (objdata.$f) {
       return Object.assign(this.constructObject(ctype), objdata.$f);
+    } else {
+      return this.namespace[ctype];
     }
   }
 }
@@ -159,7 +180,8 @@ export class Serializer {
  * Check if the argument is an instance of a class
  */
 function isObject(value: any): boolean {
-  return value instanceof Object && !Array.isArray(value);
+  return typeof value == "object" && value instanceof Object &&
+    !Array.isArray(value);
 }
 
 /**
@@ -174,7 +196,7 @@ function crawl(
   callback: (item: any) => any,
   replace = false,
   memo: any[] = [],
-) {
+): any {
   if (isObject(obj)) {
     if (memo.indexOf(obj) >= 0) {
       return obj;
@@ -183,11 +205,11 @@ function crawl(
     }
   }
 
-  if (obj !== undefined && obj !== null && typeof obj != "function") {
+  if (obj !== undefined && obj !== null) {
     const result = callback(obj);
 
     if (result === STOP_CRAWLING) {
-      return;
+      return undefined;
     }
 
     if (Array.isArray(obj)) {
@@ -244,5 +266,5 @@ function crawl(
  * Get the class name of an object.
  */
 function classname(obj: Object): string {
-  return (<any> obj.constructor).name;
+  return obj.constructor.name;
 }