[InfoExtractor] Add search methods for Next/Nuxt.js from yt-dlp

* add _search_nextjs_data(), from https://github.com/yt-dlp/yt-dlp/pull/1386
  thanks selfisekai
* add _search_nuxt_data(), from https://github.com/yt-dlp/yt-dlp/pull/1921,
  thanks Lesmiscore, pukkandan
* add tests for the above
* also fix HTML5 type recognition and tests, from
  222a230871,
  thanks Lesmiscore
* update extractors in PR using above, fix tests.

youtube_dl/extractor/common.py

@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 
 import base64
 import datetime
+import functools
 import hashlib
 import json
 import netrc
@@ -23,6 +24,7 @@ from ..compat import (
     compat_getpass,
     compat_integer_types,
     compat_http_client,
+    compat_map as map,
     compat_os_name,
     compat_str,
     compat_urllib_error,
@@ -31,6 +33,7 @@ from ..compat import (
     compat_urllib_request,
     compat_urlparse,
     compat_xml_parse_error,
+    compat_zip as zip,
 )
 from ..downloader.f4m import (
     get_base_url,
@@ -70,6 +73,7 @@ from ..utils import (
     str_or_none,
     str_to_int,
     strip_or_none,
+    traverse_obj,
     try_get,
     unescapeHTML,
     unified_strdate,
@@ -1349,6 +1353,44 @@ class InfoExtractor(object):
                     break
         return dict((k, v) for k, v in info.items() if v is not None)
 
+    def _search_nextjs_data(self, webpage, video_id, **kw):
+        nkw = dict((k, v) for k, v in kw.items() if k in ('transform_source', 'fatal'))
+        kw.pop('transform_source', None)
+        next_data = self._search_regex(
+            r'''<script[^>]+\bid\s*=\s*('|")__NEXT_DATA__\1[^>]*>(?P<nd>[^<]+)</script>''',
+            webpage, 'next.js data', group='nd', **kw)
+        if not next_data:
+            return {}
+        return self._parse_json(next_data, video_id, **nkw)
+
+    def _search_nuxt_data(self, webpage, video_id, *args, **kwargs):
+        """Parses Nuxt.js metadata. This works as long as the function __NUXT__ invokes is a pure function"""
+
+        # self, webpage, video_id, context_name='__NUXT__', *, fatal=True, traverse=('data', 0)
+        context_name = args[0] if len(args) > 0 else kwargs.get('context_name', '__NUXT__')
+        fatal = kwargs.get('fatal', True)
+        traverse = kwargs.get('traverse', ('data', 0))
+
+        re_ctx = re.escape(context_name)
+
+        FUNCTION_RE = (r'\(\s*function\s*\((?P<arg_keys>[\s\S]*?)\)\s*\{\s*'
+                       r'return\s+(?P<js>\{[\s\S]*?})\s*;?\s*}\s*\((?P<arg_vals>[\s\S]*?)\)')
+
+        js, arg_keys, arg_vals = self._search_regex(
+            (p.format(re_ctx, FUNCTION_RE) for p in
+             (r'<script>\s*window\s*\.\s*{0}\s*=\s*{1}\s*\)\s*;?\s*</script>',
+              r'{0}\s*\([\s\S]*?{1}')),
+            webpage, context_name, group=('js', 'arg_keys', 'arg_vals'),
+            default=NO_DEFAULT if fatal else (None, None, None))
+        if js is None:
+            return {}
+
+        args = dict(zip(arg_keys.split(','), map(json.dumps, self._parse_json(
+            '[{0}]'.format(arg_vals), video_id, transform_source=js_to_json, fatal=fatal) or ())))
+
+        ret = self._parse_json(js, video_id, transform_source=functools.partial(js_to_json, vars=args), fatal=fatal)
+        return traverse_obj(ret, traverse) or {}
+
     @staticmethod
     def _hidden_inputs(html):
         html = re.sub(r'<!--(?:(?!<!--).)*-->', '', html)
@@ -2496,7 +2538,8 @@ class InfoExtractor(object):
                 return f
             return {}
 
-        def _media_formats(src, cur_media_type, type_info={}):
+        def _media_formats(src, cur_media_type, type_info=None):
+            type_info = type_info or {}
             full_url = absolute_url(src)
             ext = type_info.get('ext') or determine_ext(full_url)
             if ext == 'm3u8':
@@ -2514,6 +2557,7 @@ class InfoExtractor(object):
                 formats = [{
                     'url': full_url,
                     'vcodec': 'none' if cur_media_type == 'audio' else None,
+                    'ext': ext,
                 }]
             return is_plain_url, formats
 
@@ -2522,7 +2566,7 @@ class InfoExtractor(object):
         # so we wll include them right here (see
         # https://www.ampproject.org/docs/reference/components/amp-video)
         # For dl8-* tags see https://delight-vr.com/documentation/dl8-video/
-        _MEDIA_TAG_NAME_RE = r'(?:(?:amp|dl8(?:-live)?)-)?(video|audio)'
+        _MEDIA_TAG_NAME_RE = r'(?:(?:amp|dl8(?:-live)?)-)?(video(?:-js)?|audio)'
         media_tags = [(media_tag, media_tag_name, media_type, '')
                       for media_tag, media_tag_name, media_type
                       in re.findall(r'(?s)(<(%s)[^>]*/>)' % _MEDIA_TAG_NAME_RE, webpage)]
@@ -2540,7 +2584,8 @@ class InfoExtractor(object):
             media_attributes = extract_attributes(media_tag)
             src = strip_or_none(media_attributes.get('src'))
             if src:
-                _, formats = _media_formats(src, media_type)
+                f = parse_content_type(media_attributes.get('type'))
+                _, formats = _media_formats(src, media_type, f)
                 media_info['formats'].extend(formats)
             media_info['thumbnail'] = absolute_url(media_attributes.get('poster'))
             if media_content: