Automated js/css files versioning in php

custom_helper.php

<?php
if (! function_exists('version')) {
   /**
    * Used to add file modified time for versioning css/js files.
    *
    * @param String $filePath - physical path of file.
    * @return String FilePath
    */
    function version($filePath = '')
    {
        if (file_exists($filePath)) {
            return $filePath . '?version=' . filemtime($filePath);
        }
        
        return $filePath;
    }
}
?>
<script type='text/javascript' src="<?php echo base_url(version('assets/js/Main.js')); ?>" ></script>

smart way of using filemtime :)
Extending to above, sometime the result of filemtime function are cached. In such case use clearstatcache() to clear the cache :)

Thanks Debasis for your comment :) . Will add clearstatcache() in order to clear stat cache.