Add utils.commaAndJoin() for "a, b and c" strings

src/gui/Pages/Chat/TypingMembersBar.qml

@@ -13,11 +13,8 @@ InfoBar {
     label.textFormat: Text.StyledText
     label.text: {
         const tm = typingMembers
-
         if (tm.length === 0) return ""
         if (tm.length === 1) return qsTr("%1 is typing...").arg(tm[0])
-
-        return qsTr("%1 and %2 are typing...")
-               .arg(tm.slice(0, -1).join(", ")).arg(tm.slice(-1)[0])
+        return qsTr("%1 are typing...").arg(utils.commaAndJoin(tm))
     }
 }

src/gui/Utils.qml

@@ -411,6 +411,16 @@ QtObject {
     }
 
 
+    function commaAndJoin(array) {
+        if (array.length === 0) return ""
+        if (array.length === 1) return array[0]
+
+        return qsTr("%1 and %2")
+               .arg(array.slice(0, -1).join(qsTr(", ")))
+               .arg(array.slice(-1)[0])
+    }
+
+
     function flickPages(flickable, pages, horizontal=false, multiplier=8) {
         // Adapt velocity and deceleration for the number of pages to flick.
         // If this is a repeated flicking, flick faster than a single flick.