This sanitize helper will html encode all tags and strip all attributes that aren't specifically allowed.

It also strips href/src tags with invalid protocols, like javascript: especially. It does its best to counter any tricks that hackers may use, like throwing in unicode/ascii/hex values to get past the javascript: filters. Check out the extensive test suite.

<%= sanitize @article.body %>

You can add or remove tags/attributes if you want to customize it a bit. See ActionView::Base for full docs on the available options. You can add tags/attributes for single uses of sanitize by passing either the :attributes or :tags options:

Normal Use

<%= sanitize @article.body %>

Custom Use (only the mentioned tags and attributes are allowed, nothing else)

<%= sanitize @article.body, tags: %w(table tr td), attributes: %w(id class style) %>

Add table tags to the default allowed tags

class Application < Rails::Application
  config.action_view.sanitized_allowed_tags = ['table', 'tr', 'td']
end

Remove tags to the default allowed tags

class Application < Rails::Application
  config.after_initialize do
    ActionView::Base.sanitized_allowed_tags.delete 'div'
  end
end

Change allowed default attributes

class Application < Rails::Application
  config.action_view.sanitized_allowed_attributes = ['id', 'class', 'style']
end

Please note that sanitizing user-provided text does not guarantee that the resulting markup is valid (conforming to a document type) or even well-formed. The output may still contain e.g. unescaped '<', '>', '&' characters and confuse browsers.

# File actionview/lib/action_view/helpers/sanitize_helper.rb, line 59
def sanitize(html, options = {})
  self.class.white_list_sanitizer.sanitize(html, options).try(:html_safe)
end

Sanitizes a block of CSS code. Used by sanitize when it comes across a style attribute.

# File actionview/lib/action_view/helpers/sanitize_helper.rb, line 64
def sanitize_css(style)
  self.class.white_list_sanitizer.sanitize_css(style)
end

Strips all link tags from text leaving just the link text.

strip_links('<a href="http://www.rubyonrails.org">Ruby on Rails</a>')
# => Ruby on Rails

strip_links('Please e-mail me at <a href="mailto:me@email.com">me@email.com</a>.')
# => Please e-mail me at me@email.com.

strip_links('Blog: <a href="http://www.myblog.com/" class="nav" target=\"_blank\">Visit</a>.')
# => Blog: Visit.

# File actionview/lib/action_view/helpers/sanitize_helper.rb, line 94
def strip_links(html)
  self.class.link_sanitizer.sanitize(html)
end

Strips all HTML tags from the html, including comments. This uses the html-scanner tokenizer and so its HTML parsing ability is limited by that of html-scanner.

strip_tags("Strip <i>these</i> tags!")
# => Strip these tags!

strip_tags("<b>Bold</b> no more!  <a href='more.html'>See more here</a>...")
# => Bold no more!  See more here...

strip_tags("<div id='top-bar'>Welcome to my website!</div>")
# => Welcome to my website!

# File actionview/lib/action_view/helpers/sanitize_helper.rb, line 80
def strip_tags(html)
  self.class.full_sanitizer.sanitize(html)
end