diff --git a/README.adoc b/README.adoc
index d7b15f5..b05cde0 100644
--- a/README.adoc
+++ b/README.adoc
@@ -21059,24 +21059,7 @@ Examples:
 ** link:rootfs_overlay/lkmc/nodejs/read_stdin_to_string.js[] Question: https://stackoverflow.com/questions/30441025/read-all-text-from-stdin-to-a-string
 * `class`
 ** link:rootfs_overlay/lkmc/nodejs/object_to_string.js[]: `util.inspect.custom` and `toString` override experiment: https://stackoverflow.com/questions/24902061/is-there-an-repr-equivalent-for-javascript/26698403#26698403
-+
-Output:
-+
-....
-util.inspect
-my type is MyClassUtilInspectCustom and a is 1 and b is 2
-console.log
-my type is MyClassUtilInspectCustom and a is 1 and b is 2
-toString
-[object Object]
-
-util.inspect
-MyClassToString { a: 1, b: 2 }
-console.log
-MyClassToString { a: 1, b: 2 }
-toString
-my type is MyClassToString and a is 1 and b is 2
-....
+** link:rootfs_overlay/lkmc/nodejs/object_to_json.js[]: `toJSON` examples
 * link:rootfs_overlay/lkmc/nodejs/http.js[]: `http` module to create a simple HTTP server: https://nodejs.org/api/http.html
 
 ===== NPM
diff --git a/rootfs_overlay/lkmc/nodejs/object_to_json.js b/rootfs_overlay/lkmc/nodejs/object_to_json.js
new file mode 100755
index 0000000..90e6ff7
--- /dev/null
+++ b/rootfs_overlay/lkmc/nodejs/object_to_json.js
@@ -0,0 +1,47 @@
+#!/usr/bin/env node
+
+// https://cirosantilli.com/linux-kernel-module-cheat#node-js
+
+class MyClassSub {
+  constructor(a, b) {
+    this.a = a;
+    this.b = b;
+  }
+}
+
+class MyClass {
+  constructor(a, b, sub) {
+    this.a = a;
+    this.b = b;
+    this.sub = sub;
+  }
+}
+
+console.log(JSON.stringify(new MyClass(1, 2, new MyClassSub(3, 4))));
+
+class MyClassCustomSub {
+  constructor(a, b) {
+    this.a = a;
+    this.b = b;
+  }
+  toJSON() {
+    return {
+      a: this.a,
+    }
+  }
+}
+
+class MyClassCustom {
+  constructor(a, b, sub) {
+    this.a = a;
+    this.sub = sub;
+  }
+  toJSON() {
+    return {
+      a: this.a,
+      sub: this.sub,
+    }
+  }
+}
+
+console.log(JSON.stringify(new MyClassCustom(1, 2, new MyClassCustomSub(3, 4))));
diff --git a/rootfs_overlay/lkmc/nodejs/object_to_string.js b/rootfs_overlay/lkmc/nodejs/object_to_string.js
index 66e5b47..62cbefc 100755
--- a/rootfs_overlay/lkmc/nodejs/object_to_string.js
+++ b/rootfs_overlay/lkmc/nodejs/object_to_string.js
@@ -2,29 +2,48 @@
 
 // https://cirosantilli.com/linux-kernel-module-cheat#node-js
 
-
 const util = require('util');
 
-class MyClassUtilInspectCustom {
+class MyClassUtilInspectCustomSubobject {
   constructor(a, b) {
     this.a = a;
     this.b = b;
   }
   [util.inspect.custom]() {
-    return `my type is MyClassUtilInspectCustom and a is ${this.a} and b is ${this.b}`;
+    return `my type is MyClassUtilInspectCustomSubobject and a is ${this.a} and b is ${this.b}`;
   }
 }
 
-let my_object = new MyClassUtilInspectCustom(1, 2);
+class MyClassUtilInspectCustom {
+  constructor(a, b, subobject) {
+    this.a = a;
+    this.b = b;
+    this.subobject = subobject;
+  }
+  [util.inspect.custom]() {
+    return `my type is MyClassUtilInspectCustom and a is ${this.a} and b is ${this.b} and subobject is ${util.inspect(this.subobject)}`;
+  }
+}
+
+let my_object = new MyClassUtilInspectCustom(1, 2, new MyClassUtilInspectCustomSubobject(3, 4));
+// Affected.
 console.log('util.inspect');
 console.log(util.inspect(my_object));
+// Affected.
 console.log('console.log');
 console.log(my_object);
+// Not affected.
 console.log('toString');
 console.log(my_object.toString());
+// Not affected.
+console.log('toString implicit +');
+console.log('implicit ' + my_object);
+// Not affected.
+console.log('template string');
+console.log(`${my_object}`);
 console.log();
 
-class MyClassToString {
+class MyClassToStringSubobject {
   constructor(a, b) {
     this.a = a;
     this.b = b;
@@ -34,10 +53,30 @@ class MyClassToString {
   }
 }
 
-my_object = new MyClassToString(1, 2);
+class MyClassToString {
+  constructor(a, b, subobject) {
+    this.a = a;
+    this.b = b;
+    this.subobject = subobject;
+  }
+  toString() {
+    return `my type is MyClassToString and a is ${this.a} and b is ${this.b} and subobject is ${this.subobject}`;
+  }
+}
+
+my_object = new MyClassToString(1, 2, new MyClassToStringSubobject(3, 4));
+// Affected.
 console.log('util.inspect');
 console.log(util.inspect(my_object));
+// Affected.
 console.log('console.log');
 console.log(my_object);
+// Affected.
 console.log('toString');
 console.log(my_object.toString());
+// Affected.
+console.log('toString implicit +');
+console.log('implicit ' + my_object);
+// Affected.
+console.log('template string');
+console.log(`${my_object}`);