add support for treating NaN values as equivalent (#24)

* add support for treating NaN values as equivalent

* Simplify change check

---------

Co-authored-by: Jacob Jackson <[email protected]>

Author: brainthinks

index.ts

@@ -73,6 +73,9 @@ export default function diff(
 		} else if (
 			objKey !== newObjKey &&
 			!(
+				// treat NaN values as equivalent
+				Number.isNaN(objKey) &&
+				tNumber.isNaN(newObjKey) &&
 				areCompatibleObjects &&
 				(isNaN(objKey)
 					? objKey + "" === newObjKey + ""

tests/nan.js

@@ -0,0 +1,68 @@
+import { test } from "uvu";
+import * as assert from "uvu/assert";
+import diff from "../dist/index.js";
+
+test("new NaN value in object", () => {
+	assert.equal(diff({}, { testNaN: NaN }), [
+		{
+			type: "CREATE",
+			path: ["testNaN"],
+			value: NaN,
+		},
+	]);
+});
+test("change NaN value in object", () => {
+	assert.equal(diff({ testNaN: NaN }, { testNaN: 0 }), [
+		{
+			type: "CHANGE",
+			path: ["testNaN"],
+			value: 0,
+			oldValue: NaN,
+		},
+	]);
+});
+test("do not change NaN value in object", () => {
+	assert.equal(diff({ testNaN: NaN }, { testNaN: NaN }), []);
+});
+test("remove NaN value in object", () => {
+	assert.equal(diff({ testNaN: NaN }, {}), [
+		{
+			type: "REMOVE",
+			path: ["testNaN"],
+			oldValue: NaN,
+		},
+	]);
+});
+test("new NaN value in array", () => {
+	assert.equal(diff([], [ NaN ]), [
+		{
+			type: "CREATE",
+			path: [0],
+			value: NaN,
+		},
+	]);
+});
+test("change NaN value in object", () => {
+	assert.equal(diff([ NaN ], [ 0 ]), [
+		{
+			type: "CHANGE",
+			path: [0],
+			value: 0,
+			oldValue: NaN,
+		},
+	]);
+});
+test("do not change NaN value in array", () => {
+	assert.equal(diff([ NaN ], [ NaN ]), []);
+});
+test("remove NaN value in array", () => {
+	assert.equal(diff([ NaN ], []), [
+		{
+			type: "REMOVE",
+			path: [0],
+			oldValue: NaN,
+		},
+	]);
+});
+
+test.run();