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diff --git a/12-optional-chaining/app.js b/12-optional-chaining/app.js
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+++ b/12-optional-chaining/app.js
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+const people = [
+  {
+    name: 'bob',
+    location: { street: '123 main street', timezone: { offset: '+7:00' } },
+  },
+  { name: 'peter', location: { street: '123 Pine street' } },
+  {
+    name: 'susan',
+    location: { street: '123 Apple street', timezone: { offset: '+9:00' } },
+  },
+]
+
+people.forEach((person) => {
+  // console.log(person.name)
+  // console.log(person.location)
+  // console.log(person.location.street)
+  // console.log(person.location.timezone.offset)
+  // console.log(
+  //   person.location &&
+  //     person.location.timezone &&
+  //     person.location.timezone.offset
+  // )
+  console.log(person?.location?.timezone?.offset)
+})
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+++ b/12-optional-chaining/index.html
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+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Optional Chaining</title>
+    <link rel="stylesheet" href="../global.css" />
+    <link rel="stylesheet" href="./styles.css" />
+  </head>
+  <body>
+    <h2>Optional Chaining</h2>
+    <script src="app.js"></script>
+  </body>
+</html>
diff --git a/12-optional-chaining/styles.css b/12-optional-chaining/styles.css
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