old_contents: # -*- coding: utf-8 -*-
  from classytags.core import Tag, Options
  from django import template
  from django.core.serializers.json import DjangoJSONEncoder
  from django.utils import simplejson
  from django.utils.text import javascript_quote
  
  register = template.Library()
  
  @register.filter
  def js(value):
      return simplejson.dumps(value, cls=DjangoJSONEncoder)
  
  @register.filter
  def bool(value):
      if value:
          return 'true'
      else:
          return 'false'
  
     
  class JavascriptString(Tag):
      name = 'javascript_string'
      
      options = Options(
          blocks=[
              ('end_javascript_string', 'nodelist'),
          ]
      )
      
      def render_tag(self, context, **kwargs):
          rendered = self.nodelist.render(context)
          return u"'%s'" % javascript_quote(rendered.strip())
  register.tag(JavascriptString)
  
new_contents: # -*- coding: utf-8 -*-
  from distutils.version import LooseVersion
  
  from classytags.core import Tag, Options
  import django
  from django import template
  from django.core.serializers.json import DjangoJSONEncoder
  from django.utils.text import javascript_quote
  
  DJANGO_1_4 = LooseVersion(django.get_version()) < LooseVersion('1.5')
  
  if DJANGO_1_4:
      from django.utils import simplejson as json
  else:
      import json
  
  register = template.Library()
  
  @register.filter
  def js(value):
      return json.dumps(value, cls=DjangoJSONEncoder)
  
  @register.filter
  def bool(value):
      if value:
          return 'true'
      else:
          return 'false'
  
     
  class JavascriptString(Tag):
      name = 'javascript_string'
      
      options = Options(
          blocks=[
              ('end_javascript_string', 'nodelist'),
          ]
      )
      
      def render_tag(self, context, **kwargs):
          rendered = self.nodelist.render(context)
          return u"'%s'" % javascript_quote(rendered.strip())
  register.tag(JavascriptString)
  
subject: Use json module instead of django.utils.simplejson for Django 1.5