https://ghafoorsblog.com/tags/advanced/Recent content in Advanced on Ghafoor's Personal BlogHugoenhello@ghafoorsblog.com (AG Sayyed)hello@ghafoorsblog.com (AG Sayyed)Copyright © 2024-2026 AG Sayyed. All Rights Reserved.Sun, 24 May 2026 09:13:13 +0100https://ghafoorsblog.com/posts/js/09-advanced-reference/Wed, 01 Oct 2025 08:00:00 +0000hello@ghafoorsblog.com (AG Sayyed)https://ghafoorsblog.com/posts/js/09-advanced-reference/<h2 id="how-to-read-this-post">How to read this post</h2> <p>This is the wrap-up for the JavaScript series. The previous eight posts were tutorials — they build mental models from first principles. This post is a <strong>reference</strong>: short answers to the deeper <em>&ldquo;what is this and why does it work that way&rdquo;</em> questions that the earlier tutorials hint at but rarely linger on.</p> <p>Use the headings as an index. Each section is self-contained.</p> <h2 id="type-system">Type system</h2> <h3 id="what-is-duck-typing">What is &ldquo;duck typing&rdquo;?</h3> <blockquote class="blockquote border-start ps-3 py-1 border-primary border-4"> <p><em>If it walks like a duck and quacks like a duck, treat it as a duck.</em></p>