Problem

Google Search Console reported duplicate content issues for URLs with query parameters like:

• https://rkoots.github.io/styleguide/jsguide?src=187
• https://rkoots.github.io/styleguide/jsguide?src=71
• https://rkoots.github.io/styleguide/jsguide?src=177

These URLs were being treated as separate pages without canonical URLs, causing indexing problems.

Solution Implemented

1. Enhanced Canonical Enforcer (assets/js/canonical-enforcer.js)

• Before: Used history.replaceState() which only changed browser URL
• After: Added proper redirect logic for src= parameters using:
  • Meta refresh tags for search engines
  • noindex meta tags
  • Actual HTTP redirects after processing
  • Maintained replaceState() for non-critical parameters

2. Server-Side Redirects (_redirects)

Added redirect rules to strip query parameters:

# Remove query parameters for SEO (canonical URLs)
/guide/styleguide/jsguide /guide/styleguide/jsguide/ 301
/guide/styleguide/* /guide/styleguide/:splat 301

3. HTTP Headers (_headers)

Already had proper X-Robots-Tag: noindex, nofollow for parameter URLs:

/*?*
  X-Robots-Tag: noindex, nofollow

4. Enhanced SEO Meta Tags (_includes/seo-meta-tags.html)

• Improved canonical URL generation with clean URL variable
• Added immediate JavaScript redirect for src= parameters
• Enhanced OpenGraph tags to use clean URLs
• Added conditional noindex meta tags

5. Robots.txt Protection

Already had proper blocking rule:

Disallow: /*?*

How the Solution Works

Layer 1: Prevention (robots.txt)

• Search engines are instructed not to crawl any URLs with query parameters

Layer 2: Server Headers (_headers)

• Any parameter URLs that slip through get noindex, nofollow headers
• Prevents indexing at the HTTP level

Layer 3: Server Redirects (_redirects)

• 301 redirects strip parameters and point to clean URLs
• Consolidates link equity to canonical URLs

Layer 4: Page-Level Protection (SEO meta tags)

• Conditional noindex tags for parameter URLs
• Clean canonical URLs in meta tags
• Immediate JavaScript redirect for critical parameters

Layer 5: Client-Side Enforcement (canonical-enforcer.js)

• JavaScript-based redirect and canonical tag management
• Handles edge cases and reinforces other layers

Expected Results

1. Immediate: Parameter URLs will redirect to clean URLs
2. Short-term: Google will see proper canonical tags and noindex directives
3. Medium-term: Duplicate content reports will decrease
4. Long-term: Only clean URLs will be indexed and ranked

Monitoring

Check Google Search Console for:

• Reduction in duplicate content errors
• Proper indexing of clean URLs
• No new parameter URLs being indexed

Files Modified

1. assets/js/canonical-enforcer.js - Enhanced redirect logic
2. _redirects - Added parameter stripping rules
3. _includes/seo-meta-tags.html - Enhanced meta tags and redirects

Testing

To test the solution:

1. Visit https://rkoots.github.io/guide/styleguide/jsguide?src=test
2. Should redirect to https://rkoots.github.io/guide/styleguide/jsguide/
3. Check browser network tab for redirect chain
4. Verify canonical meta tag points to clean URL