Only send Google Analytics data if analytics was loaded successfully

Prevent errors in local environment and if people are using blockers.

Author: adamwathan

docs/source/_assets/js/nav.js

@@ -52,8 +52,10 @@ $.when($.ready).then(function() {
       }, '', href)
 
       // Track on Google Analytics
-      ga('set', 'page', href)
-      ga('send', 'pageview')
+      if (typeof(ga) === 'function') {
+        ga('set', 'page', href)
+        ga('send', 'pageview')
+      }
     })
   })
 
@@ -66,8 +68,10 @@ $.when($.ready).then(function() {
       $('#content').html(e.state.content)
 
       // Track on Google Analytics
-      ga('set', 'page', e.state.href)
-      ga('send', 'pageview')
+      if (typeof(ga) === 'function') {
+        ga('set', 'page', e.state.href)
+        ga('send', 'pageview')
+      }
     }
   }