form can display but update total javascript function not working

app/views/users/_doge_buy_form.html.erb

@@ -13,7 +13,7 @@
 
   <label>
     QTY: 
-    <input id="qty" type="integer" name="doge_total" value="1" onkeyup="updateTotal()"/>
+    <input id="qty" type="integer" name="doge_total" value="1" onkeyup="updatedogeTotal()"/>
   </label> <br><br>
 
   <label>

app/views/users/show.html.erb

@@ -15,6 +15,15 @@
 
     document.getElementById('total').value = quantity * current_price ; 
   }
+
+  function updatedogeTotal(){
+
+    var quantity = document.getElementById('qty').value;
+    var current_price = document.getElementById('current_price').value;
+
+    document.getElementById('total').value = quantity * doge_price_btc ; 
+  }
+
 </script>
 
 <%= render "btc_buy_form" %>