From d7b6e9264075d9a11e130586260efe21ecd327f9 Mon Sep 17 00:00:00 2001
From: Jason Green <jasoniangreen@gmail.com>
Date: Sun, 11 Aug 2024 23:18:52 +0100
Subject: [PATCH] fix: #2482 Infinity and NaN serialise to null

---
 lib/compile/jtd/serialize.ts |  6 +++++-
 spec/jtd-schema.spec.ts      | 13 +++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/compile/jtd/serialize.ts b/lib/compile/jtd/serialize.ts
index 1d228826d4..3a0d15fcd7 100644
--- a/lib/compile/jtd/serialize.ts
+++ b/lib/compile/jtd/serialize.ts
@@ -229,7 +229,11 @@ function serializeString({gen, data}: SerializeCxt): void {
 }
 
 function serializeNumber({gen, data}: SerializeCxt): void {
-  gen.add(N.json, _`"" + ${data}`)
+  gen.if(
+    _`${data} === Infinity || ${data} === -Infinity || Number.isNaN(${data})`,
+    () => gen.add(N.json, _`null`),
+    () => gen.add(N.json, _`"" + ${data}`)
+  )
 }
 
 function serializeRef(cxt: SerializeCxt): void {
diff --git a/spec/jtd-schema.spec.ts b/spec/jtd-schema.spec.ts
index f4881b18a4..f3a400be19 100644
--- a/spec/jtd-schema.spec.ts
+++ b/spec/jtd-schema.spec.ts
@@ -146,6 +146,19 @@ describe("JSON Type Definition", () => {
     }
   })
 
+  describe("serialize special numeric values", () => {
+    const ajv = new _AjvJTD()
+
+    it(`should serialize Infinity to null`, () => {
+      const serialize = ajv.compileSerializer({type: "float64"})
+      assert.deepStrictEqual(JSON.parse(serialize(Infinity)), null)
+    })
+    it(`should serialize NaN to null`, () => {
+      const serialize = ajv.compileSerializer({type: "float64"})
+      assert.deepStrictEqual(JSON.parse(serialize(NaN)), null)
+    })
+  })
+
   describe("parse", () => {
     let ajv: AjvJTD
     before(() => (ajv = new _AjvJTD()))