Use ||= to not ignore some clickable elements, no negative tabindex

Elements with `tabindex="n"` for parseInt(n) < 0 cannot be selected by
pressing the tab key, according to the spec. If we have no other reason
to suspect that the element is clickable, we may as well ignore them.

1 files changed, 8 insertions, 7 deletions

diff --git a/content_scripts/link_hints.coffee b/content_scripts/link_hints.coffee
index fa7fa937..9eb7b87c 100644
--- a/content_scripts/link_hints.coffee
+++ b/content_scripts/link_hints.coffee
@@ -176,18 +176,19 @@ LinkHints =
         when "a"
           isClickable = true
         when "textarea"
-          isClickable = not element.disabled and not element.readOnly
+          isClickable ||= not element.disabled and not element.readOnly
         when "input"
-          unless element.getAttribute("type")?.toLowerCase() == "hidden" or
-                 element.disabled or
-                 (element.readOnly and DomUtils.isSelectable element)
-            isClickable = true
+          isClickable ||= not (element.getAttribute("type")?.toLowerCase() == "hidden" or
+                               element.disabled or
+                               (element.readOnly and DomUtils.isSelectable element))
         when "button", "select"
-          isClickable = true unless element.disabled
+          isClickable ||= not element.disabled
 
       # Elements with tabindex are sometimes useful, but usually not. We can treat them as second class
       # citizens when it improves UX, so take special note of them.
-      if element.hasAttribute("tabindex") and not isClickable
+      tabIndexValue = element.getAttribute("tabindex")
+      tabIndex = if tabIndexValue == "" then 0 else parseInt tabIndexValue
+      unless isClickable or isNaN(tabIndex) or tabIndex < 0
         isClickable = onlyHasTabIndex = true
 
       continue unless isClickable # If the element isn't clickable, do nothing.