Some examples using PHP url parameters functions like parsing the URL and getting the current URL for Wordpress useage. Also example using unparse_url() in javascript.

current-url.php

<?php
/**
 * Gets the URL of current page or requested page
 */
function bw_get_url($url) {
	if ($_SERVER['REQUEST_URI'] == '') {
			$url = ( is_ssl() ? 'https://' : 'http://' ) . $_SERVER['HTTP_HOST'] . $_SERVER['REDIRECT_URL'];
	} else { 
            $url = ( is_ssl() ? 'https://' : 'http://' ) . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
	}	
	return $url;
}



/*

Example

URL : https://gist.github.com/bryanwillis/9c13e0233c8e847693af/
Useage: echo bw_get_url($url);
Returns: https://gist.github.com/bryanwillis/9c13e0233c8e847693af/

*/

parse.php

<?php



// Gets the current URL 
function host_relative_url($parsed_url) { 
   $scheme   = isset($parsed_url['scheme']) ? $parsed_url['scheme'] . '://' : ''; 
   $host     = isset($parsed_url['host']) ? $parsed_url['host'] : ''; 
   $port     = isset($parsed_url['port']) ? ':' . $parsed_url['port'] : ''; 
   $user     = isset($parsed_url['user']) ? $parsed_url['user'] : ''; 
   $pass     = isset($parsed_url['pass']) ? ':' . $parsed_url['pass']  : ''; 
   $pass     = ($user || $pass) ? "$pass@" : ''; 
   $path     = isset($parsed_url['path']) ? $parsed_url['path'] : ''; 
   $query    = isset($parsed_url['query']) ? '?' . $parsed_url['query'] : ''; 
   $fragment = isset($parsed_url['fragment']) ? '#' . $parsed_url['fragment'] : '';
	 return "$query$fragment";
}

function check_admin_url_path() {
$url = cbs_request_uri_request_redirect();
$relative = host_relative_url(parse_url($url));
$admin_url = admin_url();
$directory   = rtrim(dirname($_SERVER['PHP_SELF']), '/\\');
$path = $admin_url;
 	echo "$relative";
	  }
add_action('all_admin_notices', 'check_admin_url_path');

parse_url.js

function parse_url($url)
{
    $dom        =   document.createElement('a');
    $dom.href   =   $url;
    $obj        =
    {
        scheme  :   $dom.protocol.substr(0, $dom.protocol.indexOf(':')),
        host    :   $dom.hostname,
        port    :   $dom.port,
        path    :   $dom.pathname,
        query   :   $dom.search.substr($dom.search.indexOf('?') + 1),
        hash    :   $dom.hash.substr($dom.hash.indexOf('#'))
    }
    return $obj;
}

relative-wordpress-urls.php

<?php
/**
 *  Relative URLs in Wordpress using unparse_url()
 */
 
class RelativeLinksPlugin {
	function __construct() {
		add_filter( 'content_save_pre', array( $this, 'make_root_relative' ) );
	}
	// Makes all of the URLs in the given string root relative for the current site
	function make_root_relative( $string ) {
		assert( is_string( $string ) );
		// The site URLs to trim
		$site_urls = array( home_url(), );
		$site_urls = apply_filters( 'relative_urls_list', $site_urls );
		// Trim each of the site URLs in hte given content
		foreach ( $site_urls as $site_url ) {
			// Remove the path from the url
			$url_bits = parse_url( $site_url );
			$url_bits['path'] = '';
			// Make URL relative in string content (for both http & https)
			foreach ( array( 'http', 'https' ) as $scheme ) {
				$url_bits['scheme'] = $scheme;
				$site_url = $this->unparse_url( $url_bits );
				$string = str_replace( $site_url, '', $string );
			}
		}
		return $string;
	}


	function unparse_url( $parsed_url ) {
		assert( ! empty( $parsed_url ) );
		$scheme   = isset( $parsed_url['scheme'] )   ? $parsed_url['scheme'] . '://' : '';
		$host     = isset( $parsed_url['host'] )     ? $parsed_url['host']           : '';
		$port     = isset( $parsed_url['port'] )     ? ':' . $parsed_url['port']     : '';
		$user     = isset( $parsed_url['user'] )     ? $parsed_url['user']           : '';
		$pass     = isset( $parsed_url['pass'] )     ? ':' . $parsed_url['pass']     : '';
		$pass     = ( $user || $pass )  ? "$pass@" : '';
		$path     = isset( $parsed_url['path'] )     ? $parsed_url['path']           : '';
		$query    = isset( $parsed_url['query'] )    ? '?' . $parsed_url['query']    : '';
		$fragment = isset( $parsed_url['fragment'] ) ? '#' . $parsed_url['fragment'] : '';
		return "$scheme$user$pass$host$port$path$query$fragment";
	}
}
// Boot
new RelativeLinksPlugin();

unparse-url.php

<?php
/**
 * Rebuilds URL from parameters
 */
 
function unparse_url($parsed_url) { 
  $scheme   = isset($parsed_url['scheme']) ? $parsed_url['scheme'] . '://' : ''; 
  $host     = isset($parsed_url['host']) ? $parsed_url['host'] : ''; 
  $port     = isset($parsed_url['port']) ? ':' . $parsed_url['port'] : ''; 
  $user     = isset($parsed_url['user']) ? $parsed_url['user'] : ''; 
  $pass     = isset($parsed_url['pass']) ? ':' . $parsed_url['pass']  : ''; 
  $pass     = ($user || $pass) ? "$pass@" : ''; 
  $path     = isset($parsed_url['path']) ? $parsed_url['path'] : ''; 
  $query    = isset($parsed_url['query']) ? '?' . $parsed_url['query'] : ''; 
  $fragment = isset($parsed_url['fragment']) ? '#' . $parsed_url['fragment'] : ''; 
  return "$scheme$user$pass$host$port$path$query$fragment"; 
}


/*

Example useage with bw_get_url($url) function

  	$current_url = bw_get_url($url);
    $parse_url  = parse_url($current_url);
  	
  	$unparsed_url = unparse_url(parse_url($current_url));
	  if ($current_url === $unparsed_url)  { 
		   print "YES, both url's equal the current URL";
	  }


Example with Wordpress:


  	$home = site_url();
  	$unparsed_url = unparse_url(parse_url($home));
	  if ($current_url === $unparsed_url)  { 
		   echo "Your on the homepage";
	  }


*/

url-directory.php

<?php
/**
 *  Get the active URL directory
 */
 
function bw_active_dir() {
  $dir = rtrim(dirname($_SERVER['PHP_SELF']), '/\\');
  return $dir;
}

/*

Example

URL : https://gist.github.com/bryanwillis/9c13e0233c8e847693af/
Useage: echo bw_active_dir();
Returns: /bryanwillis

*/