What best practices should be followed when implementing Ajax navigation in PHP to ensure compatibility with different browser functionalities?

When implementing Ajax navigation in PHP, it is important to ensure compatibility with different browser functionalities by using proper error handling and fallback mechanisms. One best practice is to check for the XMLHttpRequest object's existence before using it to make Ajax requests. Additionally, it is recommended to use a JavaScript library like jQuery to handle Ajax requests as it provides cross-browser compatibility and simplifies the code.

// Check if the XMLHttpRequest object is available
if (window.XMLHttpRequest) {
    // Code to handle Ajax requests using XMLHttpRequest
} else {
    // Fallback mechanism for browsers that do not support XMLHttpRequest
    alert('Ajax is not supported in this browser');
}