diff --git a/pywb/rewrite/regex_rewriters.py b/pywb/rewrite/regex_rewriters.py
index 571cd196..69dbef32 100644
--- a/pywb/rewrite/regex_rewriters.py
+++ b/pywb/rewrite/regex_rewriters.py
@@ -5,52 +5,118 @@ from six.moves.urllib.parse import unquote
 
 
 # =================================================================
-class RegexRewriter(StreamingRewriter):
-    # @staticmethod
-    # def comment_out(string):
-    #    return '/*' + string + '*/'
+class RxRules(object):
+    HTTPX_MATCH_STR = r'https?:\\?/\\?/[A-Za-z0-9:_@.-]+'
 
     @staticmethod
-    def format(template):
-        return lambda string: template.format(string)
-
-    @staticmethod
-    def fixed(string):
-        return lambda _: string
-
-    @staticmethod
-    def remove_https(string):
+    def remove_https(string, _):
         return string.replace("https", "http")
 
+    @staticmethod
+    def replace_str(replacer):
+        return lambda x, _: x.replace('this', replacer)
+
+    @staticmethod
+    def format(template):
+        return lambda string, _: template.format(string)
+
+    @staticmethod
+    def fixed(string):
+        return lambda _, _2: string
+
+    @staticmethod
+    def archival_rewrite():
+        return lambda string, rewriter: rewriter.rewrite(string)
+
     @staticmethod
     def add_prefix(prefix):
-        return lambda string: prefix + string
+        return lambda string, _: prefix + string
 
     @staticmethod
     def add_suffix(suffix):
-        return lambda string: string + suffix
+        return lambda string, _: string + suffix
 
     @staticmethod
-    def archival_rewrite(rewriter):
-        return lambda string: rewriter.rewrite(string)
-
-
-    HTTPX_MATCH_STR = r'https?:\\?/\\?/[A-Za-z0-9:_@.-]+'
-
-    # DEFAULT_OP = add_prefix
-
-    def __init__(self, rewriter, rules):
-        super(RegexRewriter, self).__init__(rewriter)
-        # rules = self.create_rules(http_prefix)
-
+    def compile_rules(rules):
         # Build regexstr, concatenating regex list
         regex_str = '|'.join(['(' + rx + ')' for rx, op, count in rules])
 
         # ensure it's not middle of a word, wrap in non-capture group
         regex_str = '(?<!\w)(?:' + regex_str + ')'
 
-        self.regex = re.compile(regex_str, re.M)
-        self.rules = rules
+        return re.compile(regex_str, re.M)
+
+    def __init__(self, rules=None):
+        self.rules = rules or []
+        self.regex = self.compile_rules(self.rules)
+
+    def __call__(self, extra_rules=None):
+        if not extra_rules:
+            return self.rules, self.regex
+
+        all_rules = extra_rules + self.rules
+        regex = self.compile_rules(all_rules)
+        return all_rules, regex
+
+
+# =================================================================
+class JSWombatProxyRules(RxRules):
+    def __init__(self):
+        local_init_func = '\nvar {0} = function(name) {{\
+return (self._wb_wombat && self._wb_wombat.local_init &&\
+self._wb_wombat.local_init(name)) || self[name]; }};\n\
+if (!self.__WB_pmw) {{ self.__WB_pmw = function(obj) {{ return obj; }} }}\n\
+{{\n'
+
+        local_init_func_name = '_____WB$wombat$assign$function_____'
+
+        local_var_line = 'let {0} = {1}("{0}");'
+
+        this_rw = '(this && this._WB_wombat_obj_proxy || this)'
+
+        check_loc = '(self.__WB_check_loc && self.__WB_check_loc(location) || {}).href = '
+
+        self.local_objs = [
+                      'window',
+                      'self',
+                      'document',
+                      'location',
+                      'top',
+                      'parent',
+                      'frames',
+                      'opener']
+
+
+        local_declares = '\n'.join([local_var_line.format(obj, local_init_func_name) for obj in self.local_objs])
+
+        prop_str = '|'.join(self.local_objs)
+
+        rules = [
+           (r'(?<=\.)postMessage\b\(', self.add_prefix('__WB_pmw(self).'), 0),
+           (r'(?<!\.)\blocation\b\s*[=]\s*(?![=])', self.add_suffix(check_loc), 0),
+           (r'\breturn\s+this\b\s*(?![.$])', self.replace_str(this_rw), 0),
+           (r'(?<=[\n])\s*this\b(?=(?:\.(?:{0})\b))'.format(prop_str), self.replace_str(';' + this_rw), 0),
+           (r'(?<![$.])\s*this\b(?=(?:\.(?:{0})\b))'.format(prop_str), self.replace_str(this_rw), 0),
+           (r'(?<=[=])\s*this\b\s*(?![.$])', self.replace_str(this_rw), 0),
+           ('\}(?:\s*\))?\s*\(this\)', self.replace_str(this_rw), 0),
+           (r'(?<=[^|&][|&]{2})\s*this\b\s*(?![|&.$]([^|&]|$))', self.replace_str(this_rw), 0),
+        ]
+
+        super(JSWombatProxyRules, self).__init__(rules)
+
+        self.first_buff = local_init_func.format(local_init_func_name) + local_declares
+
+        self.last_buff = '\n\n}'
+
+
+# =================================================================
+class RegexRewriter(StreamingRewriter):
+    rules_factory = RxRules()
+
+    def __init__(self, rewriter, extra_rules=None, first_buff=''):
+        super(RegexRewriter, self).__init__(rewriter, first_buff=first_buff)
+        # rules = self.create_rules(http_prefix)
+        self.rules, self.regex = self.rules_factory(extra_rules)
 
     def filter(self, m):
         return True
@@ -79,7 +145,7 @@ class RegexRewriter(StreamingRewriter):
             # if not hasattr(op, '__call__'):
             #    op = RegexRewriter.DEFAULT_OP(op)
 
-            result = op(m.group(i))
+            result = op(m.group(i), self.url_rewriter)
             final_str = result
 
             # if extracting partial match
@@ -96,11 +162,11 @@ class RegexRewriter(StreamingRewriter):
             def parse_rule(obj):
                 match = obj.get('match')
                 if 'rewrite' in obj:
-                    replace = RegexRewriter.archival_rewrite(rewriter)
+                    replace = RxRules.archival_rewrite()
                 elif 'function' in obj:
                     replace = load_py_name(obj['function'])
                 else:
-                    replace = RegexRewriter.format(obj.get('replace', '{0}'))
+                    replace = RxRules.format(obj.get('replace', '{0}'))
                 group = obj.get('group', 0)
                 result = (match, replace, group)
                 return result
@@ -111,9 +177,32 @@ class RegexRewriter(StreamingRewriter):
 
 
 # =================================================================
-class JSLinkRewriterMixin(object):
+class JSLocationRewriterRules(RxRules):
     """
-    JS Rewriter which rewrites absolute http://, https:// and // urls
+    JS Rewriter mixin which rewrites location and domain to the
+    specified prefix (default: ``WB_wombat_``)
+    """
+
+    def __init__(self, prefix='WB_wombat_'):
+        super(JSLocationRewriterRules, self).__init__(self.get_rules(prefix))
+
+    def get_rules(self, prefix):
+        rules = [
+            (r'(?<![$\'"])\b(?:location|top)\b(?![$\'":])', self.add_prefix(prefix), 0),
+
+            (r'(?<=[?])\s*(?:\w+[.])?(location)\s*(?=[:])', self.add_prefix(prefix), 1),
+
+            (r'(?<=\.)postMessage\b\(', self.add_prefix('__WB_pmw(self.window).'), 0),
+
+            (r'(?<=\.)frameElement\b', self.add_prefix(prefix), 0),
+        ]
+        return rules
+
+
+# =================================================================
+class JSLinkAndLocationRewriterRules(JSLocationRewriterRules):
+    """
+    JS Rewriter rules which also rewrite absolute http://, https:// and // urls
     at the beginning of a string
     """
     # JS_HTTPX = r'(?:(?:(?<=["\';])https?:)|(?<=["\']))\\{0,4}/\\{0,4}/[A-Za-z0-9:_@.-]+.*(?=["\s\';&\\])'
@@ -122,94 +211,44 @@ class JSLinkRewriterMixin(object):
     # JS_HTTPX = r'(?:(?<=["\';])https?:|(?<=["\']))\\{0,4}/\\{0,4}/[A-Za-z0-9:_@.-][^"\s\';&\\]*(?=["\';&\\])'
     JS_HTTPX = r'(?:(?<=["\';])https?:|(?<=["\']))\\{0,4}/\\{0,4}/[A-Za-z0-9:_@%.\\-]+/'
 
-    def __init__(self, rewriter, rules=[]):
-        rules = rules + [
-            (self.JS_HTTPX, RegexRewriter.archival_rewrite(rewriter), 0)
-        ]
-        super(JSLinkRewriterMixin, self).__init__(rewriter, rules)
+    def get_rules(self, prefix):
+        rules = super(JSLinkAndLocationRewriterRules, self).get_rules(prefix)
+        rules.append((self.JS_HTTPX, RxRules.archival_rewrite(), 0))
+        return rules
 
 
 # =================================================================
-class JSLocationRewriterMixin(object):
-    """
-    JS Rewriter mixin which rewrites location and domain to the
-    specified prefix (default: ``WB_wombat_``)
-    """
-
-    def __init__(self, rewriter, rules=[], prefix='WB_wombat_'):
-        rules = rules + [
-            (r'(?<![$\'"])\b(?:location|top)\b(?![$\'":])', RegexRewriter.add_prefix(prefix), 0),
-
-            (r'(?<=[?])\s*(?:\w+[.])?(location)\s*(?=[:])', RegexRewriter.add_prefix(prefix), 1),
-
-            (r'(?<=\.)postMessage\b\(', RegexRewriter.add_prefix('__WB_pmw(self.window).'), 0),
-
-            (r'(?<=\.)frameElement\b', RegexRewriter.add_prefix(prefix), 0),
-        ]
-        super(JSLocationRewriterMixin, self).__init__(rewriter, rules)
+class JSLocationOnlyRewriter(RegexRewriter):
+    rules_factory = JSLocationRewriterRules()
 
 
 # =================================================================
-class JSWombatProxyRewriterMixin(object):
+class JSLinkAndLocationRewriter(RegexRewriter):
+    rules_factory = JSLinkAndLocationRewriterRules()
+
+
+JSRewriter = JSLinkAndLocationRewriter
+
+# =================================================================
+class JSWombatProxyRewriter(RegexRewriter):
     """
     JS Rewriter mixin which wraps the contents of the
     script in an anonymous block scope and inserts
     Wombat js-proxy setup
     """
 
-    local_init_func = '\nvar {0} = function(name) {{\
-return (self._wb_wombat && self._wb_wombat.local_init &&\
- self._wb_wombat.local_init(name)) || self[name]; }};\n\
-if (!self.__WB_pmw) {{ self.__WB_pmw = function(obj) {{ return obj; }} }}\n\
-{{\n'
+    rules_factory = JSWombatProxyRules()
 
-    local_init_func_name = '_____WB$wombat$assign$function_____'
+    def __init__(self, rewriter, extra_rules=None):
+        super(JSWombatProxyRewriter, self).__init__(rewriter, extra_rules=extra_rules)
 
-    local_var_line = 'let {0} = {1}("{0}");'
-
-    local_objs = ['window',
-                  'self',
-                  'document',
-                  'location',
-                  'top',
-                  'parent',
-                  'frames',
-                  'opener']
-
-    THIS_RW = '(this && this._WB_wombat_obj_proxy || this)'
-
-    CHECK_LOC = '(self.__WB_check_loc && self.__WB_check_loc(location) || {}).href = '
-
-    @classmethod
-    def replace_str(cls, replacer):
-        return lambda x: x.replace('this', replacer)
-
-    def __init__(self, rewriter, rules=[]):
-        #func_rw = 'Function("return {0}")'.format(self.THIS_RW)
-        prop_str = '|'.join(self.local_objs)
-
-        rules = rules + [
-           (r'(?<=\.)postMessage\b\(', self.add_prefix('__WB_pmw(self).'), 0),
-           (r'(?<!\.)\blocation\b\s*[=]\s*(?![=])', self.add_suffix(self.CHECK_LOC), 0),
-           (r'\breturn\s+this\b\s*(?![.$])', self.replace_str(self.THIS_RW), 0),
-           (r'(?<=[\n])\s*this\b(?=(?:\.(?:{0})\b))'.format(prop_str), self.replace_str(';' + self.THIS_RW), 0),
-           (r'(?<![$.])\s*this\b(?=(?:\.(?:{0})\b))'.format(prop_str), self.replace_str(self.THIS_RW), 0),
-           (r'(?<=[=])\s*this\b\s*(?![.$])', self.replace_str(self.THIS_RW), 0),
-           ('\}(?:\s*\))?\s*\(this\)', self.replace_str(self.THIS_RW), 0),
-           (r'(?<=[^|&][|&]{2})\s*this\b\s*(?![|&.$]([^|&]|$))', self.replace_str(self.THIS_RW), 0),
-        ]
-
-        super(JSWombatProxyRewriterMixin, self).__init__(rewriter, rules)
-
-        local_declares = '\n'.join([self.local_var_line.format(obj, self.local_init_func_name) for obj in self.local_objs])
-
-        self.first_buff = self.local_init_func.format(self.local_init_func_name) + local_declares
-
-        self.last_buff = '\n\n}'
+        self.first_buff = self.rules_factory.first_buff
+        self.last_buff = self.rules_factory.last_buff
+        self.local_objs = self.rules_factory.local_objs
 
     def rewrite_complete(self, string, **kwargs):
         if not kwargs.get('inline_attr'):
-            return super(JSWombatProxyRewriterMixin, self).rewrite_complete(string)
+            return super(JSWombatProxyRewriter, self).rewrite_complete(string)
 
         # check if any of the wrapped objects are used in the script
         # if not, don't rewrite
@@ -231,31 +270,8 @@ if (!self.__WB_pmw) {{ self.__WB_pmw = function(obj) {{ return obj; }} }}\n\
         return self.last_buff
 
 
-# =================================================================
-class JSLocationOnlyRewriter(JSLocationRewriterMixin, RegexRewriter):
-    pass
-
-
-# =================================================================
-class JSLinkOnlyRewriter(JSLinkRewriterMixin, RegexRewriter):
-    pass
-
-
-# =================================================================
-class JSLinkAndLocationRewriter(JSLocationRewriterMixin,
-                                JSLinkRewriterMixin,
-                                RegexRewriter):
-    pass
-
-
 # =================================================================
 class JSNoneRewriter(RegexRewriter):
-    def __init__(self, rewriter, rules=[]):
-        super(JSNoneRewriter, self).__init__(rewriter, rules)
-
-
-# =================================================================
-class JSWombatProxyRewriter(JSWombatProxyRewriterMixin, RegexRewriter):
     pass
 
 
@@ -287,16 +303,40 @@ class JSReplaceFuzzy(object):
 
 
 # =================================================================
-# Set 'default' JSRewriter
-JSRewriter = JSLinkAndLocationRewriter
+class CSSRules(RxRules):
+    CSS_URL_REGEX = "url\\s*\\(\\s*(?:[\\\\\"']|(?:&.{1,4};))*\\s*([^)'\"]+)\\s*(?:[\\\\\"']|(?:&.{1,4};))*\\s*\\)"
+
+    CSS_IMPORT_NO_URL_REGEX = ("@import\\s+(?!url)\\(?\\s*['\"]?" +
+                               "(?!url[\\s\\(])([\w.:/\\\\-]+)")
+
+    def __init__(self):
+        rules = [
+            (self.CSS_URL_REGEX, self.archival_rewrite(), 1),
+            (self.CSS_IMPORT_NO_URL_REGEX, self.archival_rewrite(), 1),
+        ]
+
+        super(CSSRules, self).__init__(rules)
+
+# =================================================================
+class CSSRewriter(RegexRewriter):
+    rules_factory = CSSRules()
+
+
+# =================================================================
+class XMLRules(RxRules):
+    def __init__(self):
+        rules = [
+            ('([A-Za-z:]+[\s=]+)?["\'\s]*(' +
+             self.HTTPX_MATCH_STR + ')',
+             self.archival_rewrite(), 2),
+        ]
+
+        super(XMLRules, self).__init__(rules)
 
 
 # =================================================================
 class XMLRewriter(RegexRewriter):
-    def __init__(self, rewriter, extra=[]):
-        rules = self._create_rules(rewriter)
-
-        super(XMLRewriter, self).__init__(rewriter, rules)
+    rules_factory = XMLRules()
 
     # custom filter to reject 'xmlns' attr
     def filter(self, m):
@@ -306,30 +346,5 @@ class XMLRewriter(RegexRewriter):
 
         return True
 
-    def _create_rules(self, rewriter):
-        return [
-            ('([A-Za-z:]+[\s=]+)?["\'\s]*(' +
-             RegexRewriter.HTTPX_MATCH_STR + ')',
-             RegexRewriter.archival_rewrite(rewriter), 2),
-        ]
 
 
-# =================================================================
-class CSSRewriter(RegexRewriter):
-    CSS_URL_REGEX = "url\\s*\\(\\s*(?:[\\\\\"']|(?:&.{1,4};))*\\s*([^)'\"]+)\\s*(?:[\\\\\"']|(?:&.{1,4};))*\\s*\\)"
-
-    CSS_IMPORT_NO_URL_REGEX = ("@import\\s+(?!url)\\(?\\s*['\"]?" +
-                               "(?!url[\\s\\(])([\w.:/\\\\-]+)")
-
-    def __init__(self, rewriter):
-        rules = self._create_rules(rewriter)
-        super(CSSRewriter, self).__init__(rewriter, rules)
-
-    def _create_rules(self, rewriter):
-        return [
-            (CSSRewriter.CSS_URL_REGEX,
-             RegexRewriter.archival_rewrite(rewriter), 1),
-
-            (CSSRewriter.CSS_IMPORT_NO_URL_REGEX,
-             RegexRewriter.archival_rewrite(rewriter), 1),
-        ]
diff --git a/pywb/rewrite/rewrite_dash.py b/pywb/rewrite/rewrite_dash.py
index 178d6e76..595f93b5 100644
--- a/pywb/rewrite/rewrite_dash.py
+++ b/pywb/rewrite/rewrite_dash.py
@@ -58,7 +58,7 @@ class RewriteDASH(BufferedRewriter):
 
 
 # ============================================================================
-def rewrite_fb_dash(string):
+def rewrite_fb_dash(string, *args):
     DASH_SPLIT = r'\n",dash_prefetched_representation_ids:'
     inx = string.find(DASH_SPLIT)
     if inx < 0:
diff --git a/pywb/rewrite/test/test_content_rewriter.py b/pywb/rewrite/test/test_content_rewriter.py
index 97fd6fcd..9a732087 100644
--- a/pywb/rewrite/test/test_content_rewriter.py
+++ b/pywb/rewrite/test/test_content_rewriter.py
@@ -10,7 +10,7 @@ from pywb.utils.io import chunk_encode_iter
 
 from pywb.rewrite.wburl import WbUrl
 from pywb.rewrite.url_rewriter import UrlRewriter
-from pywb.rewrite.default_rewriter import DefaultRewriter
+from pywb.rewrite.default_rewriter import DefaultRewriter, RewriterWithJSProxy
 
 from pywb import get_test_dir
 
@@ -35,6 +35,7 @@ class TestContentRewriter(object):
     @classmethod
     def setup_class(self):
         self.content_rewriter = DefaultRewriter()
+        self.js_proxy_content_rewriter = RewriterWithJSProxy()
 
     def _create_response_record(self, url, headers, payload, warc_headers):
         writer = BufferWARCWriter()
@@ -53,7 +54,7 @@ class TestContentRewriter(object):
 
     def rewrite_record(self, headers, content, ts, url='http://example.com/',
                        prefix='http://localhost:8080/prefix/', warc_headers=None,
-                       request_url=None, is_live=None):
+                       request_url=None, is_live=None, use_js_proxy=True):
 
         record = self._create_response_record(url, headers, content, warc_headers)
 
@@ -68,7 +69,10 @@ class TestContentRewriter(object):
             cdx['is_fuzzy'] = '1'
         cdx['is_live'] = is_live
 
-        return self.content_rewriter(record, url_rewriter, None, cdx=cdx)
+        if use_js_proxy:
+            return self.js_proxy_content_rewriter(record, url_rewriter, None, cdx=cdx)
+        else:
+            return self.content_rewriter(record, url_rewriter, None, cdx=cdx)
 
     def test_rewrite_html(self, headers):
         content = '<html><body><a href="http://example.com/"></a></body></html>'
@@ -109,17 +113,34 @@ class TestContentRewriter(object):
         assert ('Content-Type', 'text/html') in headers.headers
 
         exp = '<html><body><a href="http://localhost:8080/prefix/201701/http://example.com/"></a></body></html>'
-        assert b''.join(gen).decode('utf-8') == exp
+
+        result = b''.join(gen).decode('utf-8')
+        assert exp == result
 
     def test_rewrite_js_mod(self, headers):
         content = 'function() { location.href = "http://example.com/"; }'
 
-        headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701js_')
+        headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701js_', use_js_proxy=False)
 
         assert ('Content-Type', 'text/javascript') in headers.headers
 
         exp = 'function() { WB_wombat_location.href = "http://example.com/"; }'
-        assert b''.join(gen).decode('utf-8') == exp
+        result = b''.join(gen).decode('utf-8')
+
+        assert exp == result
+
+    def test_rewrite_js_mod_with_obj_proxy(self, headers):
+        content = 'function() { location.href = "http://example.com/"; }'
+
+        headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701js_', use_js_proxy=True)
+
+        assert ('Content-Type', 'text/javascript') in headers.headers
+
+        exp = 'function() { location.href = "http://example.com/"; }'
+        result = b''.join(gen).decode('utf-8')
+
+        assert 'let window ' in result
+        assert exp in result
 
     def test_rewrite_cs_mod(self, headers):
         content = '.foo { background: url(http://localhost:8080/prefix/201701cs_/http://example.com/) }'
@@ -136,7 +157,7 @@ class TestContentRewriter(object):
         headers = {'Content-Type': 'application/x-javascript'}
         content = 'function() { location.href = "http://example.com/"; }'
 
-        headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701js_')
+        headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701js_', use_js_proxy=False)
 
         assert ('Content-Type', 'application/x-javascript') in headers.headers
 
@@ -281,11 +302,14 @@ class TestContentRewriter(object):
         content = '/**/ jQuery_ABC({"foo": "bar"});'
 
         headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701js_',
-                                                  url='http://example.com/path/file')
+                                                  url='http://example.com/path/file',
+                                                  use_js_proxy=True)
 
         assert ('Content-Type', 'text/javascript') in headers.headers
 
-        assert b''.join(gen).decode('utf-8') == content
+        result = b''.join(gen).decode('utf-8')
+        assert 'let window' in result
+        assert content in result
 
     def test_rewrite_text_no_type(self):
         headers = {}
@@ -307,7 +331,9 @@ class TestContentRewriter(object):
 
         assert headers.headers == [('Content-Type', 'text/javascript')]
 
-        assert b''.join(gen).decode('utf-8') == content
+        result = b''.join(gen).decode('utf-8')
+        assert 'let window ' in result
+        assert content in result
 
     def test_custom_fuzzy_replace(self):
         headers = {'Content-Type': 'application/octet-stream'}
@@ -329,7 +355,7 @@ class TestContentRewriter(object):
         content = '{"foo":"bar", "dash": {"on": "true"}, "some": ["list"]'
 
         # is_live
-        rw_headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701mp_',
+        rw_headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701js_',
                                                   url='https://player.vimeo.com/video/123445/config/config?A=B',
                                                   is_live='1')
 
@@ -342,6 +368,21 @@ class TestContentRewriter(object):
 
         assert b''.join(gen).decode('utf-8') == content
 
+    def test_custom_live_js_obj_proxy(self):
+        headers = {'Content-Type': 'text/javascript'}
+        content = '{"foo":"bar", "dash": {"on": "true"}, "some": ["list"], "hls": {"A": "B"}'
+
+        # is_live
+        rw_headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701js_',
+                                                  url='https://player.vimeo.com/video/123445/config/config?A=B',
+                                                  is_live='1',
+                                                  use_js_proxy=True)
+
+        # rewritten
+        rw_content = '{"foo":"bar", "__dash": {"on": "true"}, "some": ["list"], "__hls": {"A": "B"}'
+
+        assert rw_content in b''.join(gen).decode('utf-8')
+
     def test_custom_ajax_rewrite(self):
         headers = {'Content-Type': 'application/json',
                    'X-Pywb-Requested-With': 'XMLHttpRequest'}
@@ -451,6 +492,26 @@ http://example.com/video_4.m3u8
 </MPD>"""
         assert b''.join(gen).decode('utf-8') == filtered
 
+
+    def test_dash_fb_in_js(self):
+        headers = {'Content-Type': 'text/javascript'}
+        with open(os.path.join(get_test_dir(), 'text_content', 'sample_dash.mpd'), 'rt') as fh:
+            content = 'dash_manifest:"' + fh.read().encode('unicode-escape').decode('utf-8')
+
+        rep_ids = r'\n",dash_prefetched_representation_ids:["4","5"]'
+        content += rep_ids
+
+        headers, gen, is_rw = self.rewrite_record(headers, content, ts='201701js_',
+                                                  url='http://facebook.com/example/dash/manifest.mpd')
+
+        assert headers.headers == [('Content-Type', 'text/javascript')]
+
+        result = b''.join(gen).decode('utf-8')
+
+        # 4, 5 representations removed, replaced with default 1, 7
+        assert 'dash_prefetched_representation_ids:["1", "7"]' in result
+        assert rep_ids not in result
+
     def test_dash_custom_max_resolution(self):
         headers = {'Content-Type': 'application/dash+xml'}
         with open(os.path.join(get_test_dir(), 'text_content', 'sample_dash.mpd'), 'rt') as fh:
@@ -533,5 +594,3 @@ http://example.com/video_4.m3u8
 
         assert b''.join(gen).decode('utf-8') == filtered
 
-
-
diff --git a/pywb/rewrite/test/test_regex_rewriters.py b/pywb/rewrite/test/test_regex_rewriters.py
index 46608257..7e0070d6 100644
--- a/pywb/rewrite/test/test_regex_rewriters.py
+++ b/pywb/rewrite/test/test_regex_rewriters.py
@@ -3,7 +3,7 @@ r"""
 # Custom Regex
 #=================================================================
 # Test https->http converter (other tests below in subclasses)
->>> RegexRewriter(urlrewriter, [(RegexRewriter.HTTPX_MATCH_STR, RegexRewriter.remove_https, 0)]).rewrite('a = https://example.com; b = http://example.com; c = https://some-url/path/https://embedded.example.com')
+>>> RegexRewriter(urlrewriter, [(RxRules.HTTPX_MATCH_STR, RxRules.remove_https, 0)]).rewrite('a = https://example.com; b = http://example.com; c = https://some-url/path/https://embedded.example.com')
 'a = http://example.com; b = http://example.com; c = http://some-url/path/http://embedded.example.com'
 
 
@@ -101,7 +101,7 @@ r"""
 '"/web/20131010/\\\\/\\\\/example.com/"'
 
 # custom rules added
->>> _test_js('window.location = "http://example.com/abc.html"; some_func(); ', [('some_func\(\).*', RegexRewriter.format('/*{0}*/'), 0)])
+>>> _test_js('window.location = "http://example.com/abc.html"; some_func(); ', [('some_func\(\).*', RxRules.format('/*{0}*/'), 0)])
 'window.WB_wombat_location = "/web/20131010/http://example.com/abc.html"; /*some_func(); */'
 
 # scheme-agnostic
@@ -274,7 +274,7 @@ r"""
 
 #=================================================================
 from pywb.rewrite.url_rewriter import UrlRewriter
-from pywb.rewrite.regex_rewriters import RegexRewriter, JSRewriter, CSSRewriter, XMLRewriter
+from pywb.rewrite.regex_rewriters import RegexRewriter, JSRewriter, CSSRewriter, XMLRewriter, RxRules
 from pywb.rewrite.regex_rewriters import JSWombatProxyRewriter