diff --git a/qutebrowser/browser/webengine/webenginesettings.py b/qutebrowser/browser/webengine/webenginesettings.py
index 46bfcab59..57a4b7583 100644
--- a/qutebrowser/browser/webengine/webenginesettings.py
+++ b/qutebrowser/browser/webengine/webenginesettings.py
@@ -169,31 +169,65 @@ class WebEngineSettings(websettings.AbstractSettings):
             self._ATTRIBUTES[name] = [value]
 
 
+def _inject_early_js(profile, name, js_code, *,
+                     world=QWebEngineScript.ApplicationWorld, subframes=False):
+    """Inject the given script to run early on a page load.
+
+    This runs the script both on DocumentCreation and DocumentReady as on some
+    internal pages, DocumentCreation will not work.
+
+    That is a WORKAROUND for https://bugreports.qt.io/browse/QTBUG-66011
+    """
+    for injection in ['creation', 'ready']:
+        injection_points = {
+            'creation': QWebEngineScript.DocumentCreation,
+            'ready': QWebEngineScript.DocumentReady,
+        }
+        script = QWebEngineScript()
+        script.setInjectionPoint(injection_points[injection])
+        script.setSourceCode(js_code)
+        script.setWorldId(world)
+        script.setRunsOnSubFrames(subframes)
+        script.setName('_qute_{}_{}'.format(name, injection))
+        profile.scripts().insert(script)
+
+
+def _remove_early_js(profile, name):
+    """Remove an early QWebEngineScript."""
+    scripts = profile.scripts()
+    for injection in ['creation', 'ready']:
+        full_name = '_qute_{}_{}'.format(name, injection)
+        script = scripts.findScript(full_name)
+        if not script.isNull():
+            scripts.remove(script)
+
+
 def _init_stylesheet(profile):
     """Initialize custom stylesheets.
 
     Partially inspired by QupZilla:
     https://github.com/QupZilla/qupzilla/blob/v2.0/src/lib/app/mainapplication.cpp#L1063-L1101
     """
-    old_script = profile.scripts().findScript('_qute_stylesheet')
-    if not old_script.isNull():
-        profile.scripts().remove(old_script)
-
+    _remove_early_js(profile, 'stylesheet')
     css = shared.get_user_stylesheet()
-    source = '\n'.join([
-        '"use strict";',
-        'window._qutebrowser = window._qutebrowser || {};',
+    js_code = javascript.wrap_global(
+        'stylesheet',
         utils.read_file('javascript/stylesheet.js'),
         javascript.assemble('stylesheet', 'set_css', css),
-    ])
+    )
+    _inject_early_js(profile, 'stylesheet', js_code, subframes=True)
 
-    script = QWebEngineScript()
-    script.setName('_qute_stylesheet')
-    script.setInjectionPoint(QWebEngineScript.DocumentCreation)
-    script.setWorldId(QWebEngineScript.ApplicationWorld)
-    script.setRunsOnSubFrames(True)
-    script.setSourceCode(source)
-    profile.scripts().insert(script)
+
+def _init_js(profile):
+    """Initialize global qutebrowser JavaScript."""
+    js_code = javascript.wrap_global(
+        'scripts',
+        utils.read_file('javascript/scroll.js'),
+        utils.read_file('javascript/webelem.js'),
+        utils.read_file('javascript/caret.js'),
+    )
+    # FIXME:qtwebengine what about subframes=True?
+    _inject_early_js(profile, 'js', js_code, subframes=True)
 
 
 def _update_stylesheet():
@@ -288,6 +322,7 @@ def _update_settings(option):
 
 def _init_profile(profile):
     """Init the given profile."""
+    _init_js(profile)
     _init_stylesheet(profile)
     _set_http_headers(profile)
     _set_http_cache_size(profile)
diff --git a/qutebrowser/browser/webengine/webenginetab.py b/qutebrowser/browser/webengine/webenginetab.py
index 87adbc81e..6f4deebae 100644
--- a/qutebrowser/browser/webengine/webenginetab.py
+++ b/qutebrowser/browser/webengine/webenginetab.py
@@ -630,31 +630,10 @@ class WebEngineTab(browsertab.AbstractTab):
         self._set_widget(widget)
         self._connect_signals()
         self.backend = usertypes.Backend.QtWebEngine
-        self._init_js()
         self._child_event_filter = None
         self._saved_zoom = None
         self._reload_url = None
 
-    def _init_js(self):
-        js_code = '\n'.join([
-            '"use strict";',
-            'window._qutebrowser = window._qutebrowser || {};',
-            utils.read_file('javascript/scroll.js'),
-            utils.read_file('javascript/webelem.js'),
-            utils.read_file('javascript/caret.js'),
-        ])
-        script = QWebEngineScript()
-        # We can't use DocumentCreation here as WORKAROUND for
-        # https://bugreports.qt.io/browse/QTBUG-66011
-        script.setInjectionPoint(QWebEngineScript.DocumentReady)
-        script.setSourceCode(js_code)
-
-        page = self._widget.page()
-        script.setWorldId(QWebEngineScript.ApplicationWorld)
-
-        # FIXME:qtwebengine  what about runsOnSubFrames?
-        page.scripts().insert(script)
-
     def _install_event_filter(self):
         self._widget.focusProxy().installEventFilter(self._mouse_event_filter)
         self._child_event_filter = mouse.ChildEventFilter(
diff --git a/qutebrowser/javascript/.eslintignore b/qutebrowser/javascript/.eslintignore
index 036a72cfe..65143f360 100644
--- a/qutebrowser/javascript/.eslintignore
+++ b/qutebrowser/javascript/.eslintignore
@@ -2,3 +2,4 @@
 pac_utils.js
 # Actually a jinja template so eslint chokes on the {{}} syntax.
 greasemonkey_wrapper.js
+global_wrapper.js
diff --git a/qutebrowser/javascript/global_wrapper.js b/qutebrowser/javascript/global_wrapper.js
new file mode 100644
index 000000000..a302bd5d1
--- /dev/null
+++ b/qutebrowser/javascript/global_wrapper.js
@@ -0,0 +1,12 @@
+(function() {
+    "use strict";
+    if (!("_qutebrowser" in window)) {
+        window._qutebrowser = {"initialized": {}};
+    }
+
+    if (window._qutebrowser.initialized["{{name}}"]) {
+        return;
+    }
+    {{code}}
+    window._qutebrowser.initialized["{{name}}"] = true;
+})();
diff --git a/qutebrowser/utils/javascript.py b/qutebrowser/utils/javascript.py
index 335b1b983..93df8e70f 100644
--- a/qutebrowser/utils/javascript.py
+++ b/qutebrowser/utils/javascript.py
@@ -20,6 +20,9 @@
 """Utilities related to javascript interaction."""
 
 
+from qutebrowser.utils import jinja
+
+
 def string_escape(text):
     """Escape values special to javascript in strings.
 
@@ -70,3 +73,9 @@ def assemble(module, function, *args):
         parts = ['window', '_qutebrowser', module, function]
     code = '"use strict";\n{}({});'.format('.'.join(parts), js_args)
     return code
+
+
+def wrap_global(name, *sources):
+    """Wrap a script using window._qutebrowser."""
+    template = jinja.js_environment.get_template('global_wrapper.js')
+    return template.render(code='\n'.join(sources), name=name)
diff --git a/tests/unit/utils/test_javascript.py b/tests/unit/utils/test_javascript.py
index 864483bf0..29e090fd0 100644
--- a/tests/unit/utils/test_javascript.py
+++ b/tests/unit/utils/test_javascript.py
@@ -100,3 +100,12 @@ def test_convert_js_arg(arg, expected):
 def test_assemble(base, expected_base):
     expected = '"use strict";\n{}.func(23);'.format(expected_base)
     assert javascript.assemble(base, 'func', 23) == expected
+
+
+def test_wrap_global():
+    source = javascript.wrap_global('name',
+                                    'console.log("foo");',
+                                    'console.log("bar");')
+    assert 'window._qutebrowser.initialized["name"]' in source
+    assert 'console.log("foo");' in source
+    assert 'console.log("bar");' in source