Methods
H
J
Constants
HTML_ESCAPE = { '&' => '&amp;', '>' => '&gt;', '<' => '&lt;', '"' => '&quot;', "'" => '&#39;' }
 
JSON_ESCAPE = { '&' => '\u0026', '>' => '\u003E', '<' => '\u003C' }
 
HTML_ESCAPE_ONCE_REGEXP = /["><']|&(?!([a-zA-Z]+|(#\d+));)/
 
JSON_ESCAPE_REGEXP = /[&"><]/
 
Class Public methods
h(s)
html_escape(s)

A utility method for escaping HTML tag characters. This method is also aliased as h.

In your ERB templates, use this method to escape any unsafe content. For example:

<%=h @person.name %>

puts html_escape('is a > 0 & a < 10?')
# => is a &gt; 0 &amp; a &lt; 10?
Also aliased as: h

Source: show | on GitHub 

# File activesupport/lib/active_support/core_ext/string/output_safety.rb, line 19
def html_escape(s)
  s = s.to_s
  if s.html_safe?
    s
  else
    s.gsub(/[&"'><]/, HTML_ESCAPE).html_safe
  end
end
html_escape_once(s)

A utility method for escaping HTML without affecting existing escaped entities.

html_escape_once('1 < 2 &amp; 3')
# => "1 &lt; 2 &amp; 3"

html_escape_once('&lt;&lt; Accept & Checkout')
# => "&lt;&lt; Accept &amp; Checkout"

Source: show | on GitHub 

# File activesupport/lib/active_support/core_ext/string/output_safety.rb, line 44
def html_escape_once(s)
  result = s.to_s.gsub(HTML_ESCAPE_ONCE_REGEXP, HTML_ESCAPE)
  s.html_safe? ? result.html_safe : result
end
json_escape(s)

A utility method for escaping HTML entities in JSON strings using uXXXX JavaScript escape sequences for string literals:

json_escape('is a > 0 & a < 10?')
# => is a \u003E 0 \u0026 a \u003C 10?

Note that after this operation is performed the output is not valid JSON. In particular double quotes are removed:

json_escape('{"name":"john","created_at":"2010-04-28T01:39:31Z","id":1}')
# => {name:john,created_at:2010-04-28T01:39:31Z,id:1}

Source: show | on GitHub 

# File activesupport/lib/active_support/core_ext/string/output_safety.rb, line 62
def json_escape(s)
  result = s.to_s.gsub(JSON_ESCAPE_REGEXP, JSON_ESCAPE)
  s.html_safe? ? result.html_safe : result
end