Component-Based UI — Complete Guide
Component-Based UI — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of HTML Tutorial on Toolliyo Academy.
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HTML Tutorial · Lesson 67 of 100
Component-Based UI
Basics ✓ → Forms & semantics ✓ → APIs & performance → Projects
APIs & performance · 3 — HTML5, CSS/JS, security · ~10 min · HTML — with CSS & JavaScript
What is this?
UI components bundle markup, styles, and behavior into reusable pieces.
Why should you care?
MarkupVerse alert banners and stat cards repeat across dashboards with one pattern.
See it live — copy this example
Save as demo.html and open in your browser, or use Run Example below.
<div class="mv-alert mv-alert--warning" role="status">
<strong class="mv-alert__title">Session expiring</strong>
<p class="mv-alert__body">You will be signed out in 2 minutes.</p>
<button type="button" class="mv-alert__action">Stay signed in</button>
</div>Run Example »
Edit the code below and click Run to see the result in Toolliyo’s live editor.
What happened?
- Name blocks (mv-alert), elements (__title), modifiers (--warning).
- Same HTML contract everywhere.
Practice next
- Copy alert block markup.
- Swap modifier for error variant.
- Wire action button in JS once.
- Add mv-alert--success variant.
- Nest alert inside a form fieldset.
Remember
Block/element/modifier. role=status for live info. Reuse HTML contract.
MarkupVerse session alert
Banking and SaaS both use mv-alert.
Outcome: Consistent warning UI across products.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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