feat: serialize bigints for islands (#1317)

docs/concepts/islands.md

@@ -34,9 +34,9 @@ care of automatically re-hydrating the island on the client.
 Passing props to islands is supported, but only if the props are serializable.
 Fresh can serialize the following types of values:
 
-- Primitive types `string`, `boolean`, and `null`
+- Primitive types `string`, `boolean`, `bigint`, and `null`
 - Most `number`s (`Infinity`, `-Infinity`, and `NaN` are silently converted to
-  `null`, and `bigint`s are not supported)
+  `null`)
 - Plain objects with string keys and serializable values
 - Arrays containing serializable values
 - Uint8Array

src/runtime/deserializer.ts

@@ -29,6 +29,9 @@ export function deserialize(
       if (v[KEY] === "s") {
         return signal!(v.v);
       }
+      if (v[KEY] === "b") {
+        return BigInt(v.d);
+      }
       if (v[KEY] === "u8a") {
         return b64decode(v.d);
       }

src/server/__snapshots__/serializer_test.ts.snap

@@ -2,6 +2,8 @@ export const snapshot = {};
 
 snapshot[`serializer - primitives & plain objects 1`] = `'{"v":{"a":1,"b":"2","c":true,"d":null,"f":[1,2,3],"g":{"a":1,"b":2,"c":3}}}'`;
 
+snapshot[`serializer - bigint 1`] = `'{"v":{"a":{"_f":"b","d":"999999999999999999"}}}'`;
+
 snapshot[`serializer - Uint8Array 1`] = `'{"v":{"a":{"_f":"u8a","d":"AQID"}}}'`;
 
 snapshot[`serializer - signals 1`] = `'{"v":{"a":1,"b":{"_f":"s","v":2}}}'`;

src/server/serializer.ts

@@ -5,6 +5,7 @@
  * - `null`
  * - `boolean`
  * - `number`
+ * - `bigint`
  * - `string`
  * - `array`
  * - `object` (no prototypes)
@@ -134,6 +135,11 @@ export function serialize(data: unknown): SerializeResult {
       const res = { [KEY]: "s", v: value.peek() };
       parentStack.push(res);
       return res;
+    } else if (typeof value === "bigint") {
+      requiresDeserializer = true;
+      const res = { [KEY]: "b", d: value.toString() };
+      parentStack.push(res);
+      return res;
     } else if (value instanceof Uint8Array) {
       requiresDeserializer = true;
       const res = { [KEY]: "u8a", d: b64encode(value) };

src/server/serializer_test.ts

@@ -22,6 +22,16 @@ Deno.test("serializer - primitives & plain objects", async (t) => {
   assertEquals(deserialized, data);
 });
 
+Deno.test("serializer - bigint", async (t) => {
+  const data = { a: 999999999999999999n };
+  const res = serialize(data);
+  assert(res.requiresDeserializer);
+  assert(!res.hasSignals);
+  await assertSnapshot(t, res.serialized);
+  const deserialized = deserialize(res.serialized);
+  assertEquals(deserialized, data);
+});
+
 Deno.test("serializer - Uint8Array", async (t) => {
   const data = { a: new Uint8Array([1, 2, 3]) };
   const res = serialize(data);