Common Implementation Patterns

Progressive Web App (PWA) Configuration

// PWA with necessary permissions
app.use((req, res, next) => {
    if (req.path.startsWith('/app')) {
        // PWA needs certain features
        res.setHeader('Permissions-Policy',
            'geolocation=(self), ' +
            'camera=(self), ' +
            'microphone=(self), ' +
            'notifications=(self), ' +
            'push=(self), ' +
            'sync-xhr=(), ' +
            'magnetometer=(), ' +
            'gyroscope=()'
        );
    } else {
        // Restrictive policy for other pages
        res.setHeader('Permissions-Policy',
            'camera=(), microphone=(), geolocation=(), payment=()'
        );
    }
    next();
});

Third-Party Widget Integration

// Secure third-party widget embedding
function embedThirdPartyWidget(widgetUrl, container, allowedFeatures = []) {
    const iframe = document.createElement('iframe');
    iframe.src = widgetUrl;
    iframe.style.width = '100%';
    iframe.style.height = '400px';
    iframe.style.border = 'none';
    
    // Set restrictive permissions by default
    const permissions = {
        'camera': "'none'",
        'microphone': "'none'",
        'geolocation': "'none'",
        'payment': "'none'",
        'usb': "'none'",
        'bluetooth': "'none'"
    };
    
    // Allow specific features
    allowedFeatures.forEach(feature => {
        permissions[feature] = "'self'";
    });
    
    const allowAttribute = Object.entries(permissions)
        .map(([k, v]) => `${k} ${v}`)
        .join('; ');
    
    iframe.setAttribute('allow', allowAttribute);
    iframe.setAttribute('sandbox', 'allow-scripts allow-same-origin allow-forms');
    
    container.appendChild(iframe);
}

// Usage
embedThirdPartyWidget(
    'https://chat-widget.example.com',
    document.getElementById('chat-container'),
    ['microphone', 'camera'] // Only allow necessary features
);