Refactor stubs for gettext JS function (#5170)

src/pretix/static/pretixbase/js/gettextstub.js

@@ -0,0 +1,23 @@
+// The actual gettext implementation is loaded asynchronously with the translation
+function gettext(msgid) {
+    if (typeof django !== 'undefined' && typeof django.gettext !== 'undefined') {
+        return django.gettext(msgid);
+    }
+    return msgid;
+}
+
+function ngettext(singular, plural, count) {
+    if (typeof django !== 'undefined' && typeof django.ngettext !== 'undefined') {
+        return django.ngettext(singular, plural, count);
+    }
+    return plural;
+}
+
+function interpolate(fmt, object, named) {
+    if (named) {
+        return fmt.replace(/%\(\w+\)s/g, function(match){return String(obj[match.slice(2,-2)])});
+    } else {
+        return fmt.replace(/%s/g, function(match){return String(obj.shift())});
+    }
+}
+