HtmlSanitizer Component
=======================
The HtmlSanitizer component provides an object-oriented API to sanitize
untrusted HTML input for safe insertion into a document's DOM.
Usage
-----
```php
use Symfony\Component\HtmlSanitizer\HtmlSanitizerConfig;
use Symfony\Component\HtmlSanitizer\HtmlSanitizer;
// By default, an element not added to the allowed or blocked elements
// will be dropped, including its children
$config = (new HtmlSanitizerConfig())
// Allow "safe" elements and attributes. All scripts will be removed
// as well as other dangerous behaviors like CSS injection
->allowSafeElements()
// Allow all static elements and attributes from the W3C Sanitizer API
// standard. All scripts will be removed but the output may still contain
// other dangerous behaviors like CSS injection (click-jacking), CSS
// expressions, ...
->allowStaticElements()
// Allow the "div" element and no attribute can be on it
->allowElement('div')
// Allow the "a" element, and the "title" attribute to be on it
->allowElement('a', ['title'])
// Allow the "span" element, and any attribute from the Sanitizer API is allowed
// (see https://wicg.github.io/sanitizer-api/#default-configuration)
->allowElement('span', '*')
// Block the "section" element: this element will be removed but
// its children will be retained
->blockElement('section')
// Drop the "div" element: this element will be removed, including its children
->dropElement('div')
// Allow the attribute "title" on the "div" element
->allowAttribute('title', ['div'])
// Allow the attribute "data-custom-attr" on all currently allowed elements
->allowAttribute('data-custom-attr', '*')
// Drop the "data-custom-attr" attribute from the "div" element:
// this attribute will be removed
->dropAttribute('data-custom-attr', ['div'])
// Drop the "data-custom-attr" attribute from all elements:
// this attribute will be removed
->dropAttribute('data-custom-attr', '*')
// Forcefully set the value of all "rel" attributes on "a"
// elements to "noopener noreferrer"
->forceAttribute('a', 'rel', 'noopener noreferrer')
// Transform all HTTP schemes to HTTPS
->forceHttpsUrls()
// Configure which schemes are allowed in links (others will be dropped)
->allowLinkSchemes(['https', 'http', 'mailto'])
// Configure which hosts are allowed in links (by default all are allowed)
->allowLinkHosts(['symfony.com', 'example.com'])
// Allow relative URL in links (by default they are dropped)
->allowRelativeLinks()
// Configure which schemes are allowed in img/audio/video/iframe (others will be dropped)
->allowMediaSchemes(['https', 'http'])
// Configure which hosts are allowed in img/audio/video/iframe (by default all are allowed)
->allowMediaHosts(['symfony.com', 'example.com'])
// Allow relative URL in img/audio/video/iframe (by default they are dropped)
->allowRelativeMedias()
// Configure a custom attribute sanitizer to apply custom sanitization logic
// ($attributeSanitizer instance of AttributeSanitizerInterface)
->withAttributeSanitizer($attributeSanitizer)
// Unregister a previously registered attribute sanitizer
// ($attributeSanitizer instance of AttributeSanitizerInterface)
->withoutAttributeSanitizer($attributeSanitizer)
;
$sanitizer = new HtmlSanitizer($config);
// Sanitize a given string, using the configuration provided and in the
// "body" context (tags only allowed in will be removed)
$sanitizer->sanitize($userInput);
// Sanitize the given string for a usage in a tag
$sanitizer->sanitizeFor('head', $userInput);
// Sanitize the given string for a usage in another tag
$sanitizer->sanitizeFor('title', $userInput); // Will encode as HTML entities
$sanitizer->sanitizeFor('textarea', $userInput); // Will encode as HTML entities
$sanitizer->sanitizeFor('div', $userInput); // Will sanitize as body
$sanitizer->sanitizeFor('section', $userInput); // Will sanitize as body
// ...
```
Resources
---------
* [Contributing](https://symfony.com/doc/current/contributing/index.html)
* [Report issues](https://github.com/symfony/symfony/issues) and
[send Pull Requests](https://github.com/symfony/symfony/pulls)
in the [main Symfony repository](https://github.com/symfony/symfony)