1 files changed, 10 insertions, 6 deletions
diff --git a/activesupport/lib/active_support/json/encoding.rb b/activesupport/lib/active_support/json/encoding.rb
index 0e1bf4c40b..ef45a546b6 100644
--- a/activesupport/lib/active_support/json/encoding.rb
+++ b/activesupport/lib/active_support/json/encoding.rb
@@ -1,7 +1,6 @@
 require 'active_support/core_ext/object/to_json'
 require 'active_support/core_ext/module/delegation'
 require 'active_support/json/variable'
-require 'active_support/ordered_hash'
 
 require 'bigdecimal'
 require 'active_support/core_ext/big_decimal/conversions' # for #to_s
@@ -148,8 +147,8 @@ class Object
   end
 end
 
-class Struct
-  def as_json(options = nil) #:nodoc:
+class Struct #:nodoc:
+  def as_json(options = nil)
     Hash[members.zip(values)]
   end
 end
@@ -183,6 +182,12 @@ class Numeric
   def encode_json(encoder) to_s end #:nodoc:
 end
 
+class Float
+  # Encoding Infinity or NaN to JSON should return "null". The default returns
+  # "Infinity" or "NaN" what breaks parsing the JSON. E.g. JSON.parse('[NaN]').
+  def as_json(options = nil) finite? ? self : NilClass::AS_JSON end #:nodoc:
+end
+
 class BigDecimal
   # A BigDecimal would be naturally represented as a JSON number. Most libraries,
   # however, parse non-integer JSON numbers directly as floats. Clients using
@@ -192,7 +197,7 @@ class BigDecimal
   # That's why a JSON string is returned. The JSON literal is not numeric, but if
   # the other end knows by contract that the data is supposed to be a BigDecimal,
   # it still has the chance to post-process the string and get the real value.
-  def as_json(options = nil) to_s end #:nodoc:
+  def as_json(options = nil) finite? ? to_s : NilClass::AS_JSON end #:nodoc:
 end
 
 class Regexp
@@ -239,8 +244,7 @@ class Hash
 
     # use encoder as a proxy to call as_json on all values in the subset, to protect from circular references
     encoder = options && options[:encoder] || ActiveSupport::JSON::Encoding::Encoder.new(options)
-    result = self.is_a?(ActiveSupport::OrderedHash) ? ActiveSupport::OrderedHash : Hash
-    result[subset.map { |k, v| [k.to_s, encoder.as_json(v, options)] }]
+    Hash[subset.map { |k, v| [k.to_s, encoder.as_json(v, options)] }]
   end
 
   def encode_json(encoder)