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HTML · Question Set
Best Practices & Standards (Advanced) interview questions for placements and exams.
Questions
14
Included in this set
Subject
HTML
Explore more sets
Difficulty
Mixed
Level of this set
Go through each question and its explanation. Use this set as a focused practice pack for HTML.
Web Content Accessibility Guidelines (WCAG) are based on four key principles: perceivable, operable, understandable, and robust (POUR). ‘Invisible’ is not part of these standards.
<!-- Example: adding alt text for accessibility --> <img src="logo.png" alt="Company logo">
For complete preparation, combine this set with full subject-wise practice for HTML. You can also explore other subjects and sets from the links below.
HTML validation checks whether your code follows the official W3C standards. It helps detect missing tags, incorrect nesting, and deprecated attributes. Valid code ensures better cross-browser compatibility, accessibility, and maintainability.
<!-- Validate your HTML --> <p>Use the W3C Markup Validation Service at https://validator.w3.org/</p>
Mobile-first design focuses on creating responsive layouts that prioritize smaller screens first, then enhance for larger screens. It ensures usability and performance for mobile users and follows modern responsive design principles.
@media (min-width: 768px) {
/* Enhance layout for larger screens */
}Progressive enhancement focuses on building a basic, functional version of a website that works everywhere. Then, developers layer on enhanced features for browsers that support them. This improves accessibility and ensures broader reach.
<!-- Basic HTML -->
<button>Submit</button>
<!-- Enhanced with JavaScript -->
<script>
document.querySelector('button').addEventListener('click', () => alert('Form submitted!'));
</script>HTML validators like the W3C Markup Validation Service check code against official HTML standards. They detect errors such as missing attributes, unclosed tags, and outdated elements. Validation ensures consistent rendering, accessibility compliance, and helps maintain a professional, bug-free codebase.
<!-- Example usage --> <p>Check your code using: https://validator.w3.org/</p>
Consistent indentation, lowercase tags, and proper line spacing improve code readability and collaboration. Good formatting helps maintainability and reduces the chance of structural errors in complex layouts.
<!-- Well-formatted HTML example -->
<main>
<section>
<h2>Good Formatting</h2>
<p>This is an example of well-indented HTML.</p>
</section>
</main>Using lowercase letters with hyphens (kebab-case) or underscores (snake_case) improves consistency and readability. Avoid using spaces or special characters. For example, use main-header or user_profile instead of mixedCase or random naming.
<!-- Example of consistent naming --> <div id="main-header" class="user-profile"> <h1>Welcome</h1> </div>
Comments help document sections of your code, making it easier for others (and your future self) to understand the structure and logic. They do not affect how the page is rendered by the browser.
<!-- This section contains the main navigation --> <nav>...</nav>
To ensure consistent rendering across browsers, developers may use vendor prefixes like -webkit-, -moz-, or -ms- for experimental CSS features. Testing on multiple browsers and validating HTML/CSS are also crucial for compatibility.
/* Example: cross-browser prefixes */
.box {
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;
}Unclosed or improperly nested tags can break layouts and cause accessibility or SEO issues. Always validate and close your tags properly.
<!-- Incorrect --> <p><strong>Bold text<p></strong> <!-- Correct --> <p><strong>Bold text</strong></p>
Reducing HTTP requests, compressing images, and deferring non-critical scripts improve performance. Efficient markup and resource management create faster, user-friendly experiences.
<!-- Example: optimized image --> <img src="image.webp" alt="Optimized image" loading="lazy">
The W3C is the main international body responsible for defining and maintaining web standards including HTML, CSS, and accessibility guidelines. Adhering to W3C standards ensures interoperability and reliability.
<!-- W3C Validation Link --> <a href="https://validator.w3.org/">Validate HTML</a>
Progressive enhancement builds a basic functional experience first, ensuring accessibility for all users and browsers. Then, advanced features like animations, JavaScript, or APIs are layered on for modern browsers. For example, a form should work with basic HTML submission first, then be enhanced with AJAX for smoother performance.
<!-- Basic form --> <form action="/submit" method="POST"> <input type="text" name="name"> <button>Submit</button> </form> <!-- Enhanced with JavaScript --> <script> // AJAX form enhancement </script>
Common HTML mistakes include unclosed tags, improper nesting, missing alt attributes for images, using inline styles excessively, and ignoring validation errors. Other errors include mixing semantic meaning with presentation, skipping accessibility tags, and using outdated elements. Avoiding these mistakes ensures cleaner, more maintainable, and accessible code.
<!-- Wrong --> <div><p>Paragraph<div></p> <!-- Correct --> <div><p>Paragraph</p></div>