Script Blocking Guide

Understanding Script Blocking

Script blocking prevents potentially harmful or unwanted JavaScript from executing. Key targets include:

  • Tracking scripts
  • Analytics code
  • Advertisement scripts
  • Cryptominers

Blocking Methods

Content Security Policy (CSP)

Content-Security-Policy: script-src 'self' 
  'unsafe-inline' 'unsafe-eval' 
  https://trusted-domain.com;

Filter Rules

||analytics.com/script.js$script
domain.com##script:contains(tracking)
*$script,domain=ads.com

Tools and Extensions

NoScript

  • Granular script control
  • Domain whitelisting
  • XSS protection
  • Temporary permissions

uMatrix

  • Resource type control
  • Per-site rules
  • Matrix interface
  • Rule persistence

Script Types to Block

  • Third-party analytics
  • Social media widgets
  • Behavioral tracking
  • Performance monitoring
  • Advertisement delivery

Implementation Strategies

Selective Blocking

  • Whitelist approach
  • Domain-based rules
  • Content analysis
  • Behavior monitoring

Global Policies

  • Default-deny rules
  • Trusted sources
  • Update management
  • Exception handling

Common Challenges

  • Website functionality
  • False positives
  • Dynamic content
  • Script dependencies

Best Practices

  • Regular rule updates
  • Performance monitoring
  • Security testing
  • User feedback

Advanced Techniques

Script Injection Prevention

// CSP Header
script-src 'nonce-random123' 'strict-dynamic';

// HTML Example (commented to prevent Vue parsing)
<!-- <script nonce="random123"> -->
<!-- // Trusted code -->
<!-- </script> -->

Resource Monitoring

// Performance API
performance.getEntriesByType('resource')
  .filter(r => r.initiatorType === 'script');