Remove needs_js for @cmdutils.register

This gets rid of a QtWebKit import in commands.py, and also makes those
checks work later when we have per-domain settings.

qutebrowser/browser/browsertab.py

@@ -715,6 +715,10 @@ class AbstractTab(QWidget):
         """
         raise NotImplementedError
 
+    def has_js(self):
+        """Check if qutebrowser can run javascript in this tab."""
+        raise NotImplementedError
+
     def shutdown(self):
         raise NotImplementedError
 

qutebrowser/browser/commands.py

@@ -1496,7 +1496,7 @@ class CommandDispatcher:
     @cmdutils.register(instance='command-dispatcher',
                        deprecated="Use :insert-text {primary}",
                        modes=[KeyMode.insert], hide=True, scope='window',
-                       needs_js=True, backend=usertypes.Backend.QtWebKit)
+                       backend=usertypes.Backend.QtWebKit)
     def paste_primary(self):
         """Paste the primary selection at cursor position."""
         try:
@@ -1505,8 +1505,7 @@ class CommandDispatcher:
             self.insert_text(utils.get_clipboard())
 
     @cmdutils.register(instance='command-dispatcher', maxsplit=0,
-                       scope='window', needs_js=True,
-                       backend=usertypes.Backend.QtWebKit)
+                       scope='window', backend=usertypes.Backend.QtWebKit)
     def insert_text(self, text):
         """Insert text at cursor position.
 
@@ -1515,6 +1514,8 @@ class CommandDispatcher:
         """
         # FIXME:qtwebengine have a proper API for this
         tab = self._current_widget()
+        if not tab.has_js():
+            raise cmdexc.CommandError("This command needs javascript enabled.")
         page = tab._widget.page()  # pylint: disable=protected-access
         try:
             elem = webkitelem.focus_elem(page.currentFrame())

qutebrowser/browser/webengine/webenginetab.py

@@ -458,6 +458,10 @@ class WebEngineTab(browsertab.AbstractTab):
             else:
                 self._widget.page().runJavaScript(code, callback)
 
+    def has_js(self):
+        # QtWebEngine can run JS even if the page can't
+        return True
+
     def shutdown(self):
         log.stub()
 

qutebrowser/browser/webkit/webkittab.py

@@ -618,6 +618,10 @@ class WebKitTab(browsertab.AbstractTab):
         if callback is not None:
             callback(result)
 
+    def has_js(self):
+        settings = QWebSettings.globalSettings()
+        return settings.testAttribute(QWebSettings.JavascriptEnabled)
+
     def icon(self):
         return self._widget.icon()
 

qutebrowser/commands/command.py

@@ -23,8 +23,6 @@ import inspect
 import collections
 import traceback
 
-from PyQt5.QtWebKit import QWebSettings
-
 from qutebrowser.commands import cmdexc, argparser
 from qutebrowser.utils import (log, utils, message, docutils, objreg,
                                usertypes, typing)
@@ -83,7 +81,6 @@ class Command:
                  both)
         no_replace_variables: Don't replace variables like {url}
         _qute_args: The saved data from @cmdutils.argument
-        _needs_js: Whether the command needs javascript enabled
         _modes: The modes the command can be executed in.
         _not_modes: The modes the command can not be executed in.
         _count: The count set for the command.
@@ -92,10 +89,10 @@ class Command:
     """
 
     def __init__(self, *, handler, name, instance=None, maxsplit=None,
-                 hide=False, modes=None, not_modes=None, needs_js=False,
-                 debug=False, ignore_args=False, deprecated=False,
-                 no_cmd_split=False, star_args_optional=False, scope='global',
-                 backend=None, no_replace_variables=False):
+                 hide=False, modes=None, not_modes=None, debug=False,
+                 ignore_args=False, deprecated=False, no_cmd_split=False,
+                 star_args_optional=False, scope='global', backend=None,
+                 no_replace_variables=False):
         # I really don't know how to solve this in a better way, I tried.
         # pylint: disable=too-many-locals
         if modes is not None and not_modes is not None:
@@ -120,7 +117,6 @@ class Command:
         self._modes = modes
         self._not_modes = not_modes
         self._scope = scope
-        self._needs_js = needs_js
         self._star_args_optional = star_args_optional
         self.debug = debug
         self.ignore_args = ignore_args
@@ -171,10 +167,6 @@ class Command:
                 "{}: This command is not allowed in {} mode.".format(
                     self.name, mode_names))
 
-        if self._needs_js and not QWebSettings.globalSettings().testAttribute(
-                QWebSettings.JavascriptEnabled):
-            raise cmdexc.PrerequisitesError(
-                "{}: This command needs javascript enabled.".format(self.name))
         used_backend = usertypes.arg2backend[objreg.get('args').backend]
         if self.backend is not None and used_backend != self.backend:
             raise cmdexc.PrerequisitesError(