Change record status: 
Project: 
Introduced in branch: 
8.x
Description: 

URL related functions like have moved to the UrlHelper component.

Specifically:

drupal_get_query_parameters
drupal_parse_url
drupal_encode_path
url_is_external
drupal_get_query_array
filter_xss_bad_protocol

D7

<?php
drupal_get_query_parameters
('foo=bar&bar=baz');
drupal_parse_url('http://localhost/test?foo=bar&bar=baz');
drupal_encode_path('drupal');
url_is_external('http://drupal.org');
$query_array = drupal_get_query_array('foo=bar&bar=baz');
filter_xss_bad_protocol('javascript://example.com?foo&bar');
?>

D8

<?php
use \Drupal\Component\Utility\UrlHelper;
UrlHelper::filterQueryParameters('foo=bar&bar=baz');
UrlHelper::parse('http://localhost/test?foo=bar&bar=baz');
UrlHelper::encodePath('drupal');
UrlHelper::isExternal('http://drupal.org');
parse_str('foo=bar&bar=baz', $query_array);
UrlHelper::filterBadProtocol('javascript://example.com?foo&bar');
?>
Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done