What potential pitfalls should be considered when modifying HTML output in PHP functions like getContent()?

When modifying HTML output in PHP functions like getContent(), potential pitfalls to consider include introducing security vulnerabilities such as cross-site scripting (XSS) attacks if user input is not properly sanitized, breaking the structure or styling of the HTML if the modifications are not done carefully, and negatively impacting the performance of the website if the modifications are inefficient or resource-intensive. To mitigate these risks, always sanitize user input, use proper HTML markup and styling techniques, and optimize the code for better performance.

// Example of sanitizing user input in getContent() function
function getContent($content) {
    // Sanitize user input to prevent XSS attacks
    $sanitizedContent = htmlspecialchars($content, ENT_QUOTES, 'UTF-8');
    
    // Perform other modifications to the content
    // ...
    
    return $sanitizedContent;
}