add a link click gtag event send

www/js/tajian.js

@@ -764,4 +764,13 @@ if ($('.cookie-banner').get(0)) {
     });
 }
 
+// ga event send
+$('a').click(function(e) {
+    try {
+        gtag('event', 'click_a_link', {'link': e.target.href});
+    }catch(err) {
+        console.error('GA event fire failed', err);
+    }
+});
+
 })();