Added a check to make sure the server doesn't exist before creating it

public/js/drake.js

@@ -1,7 +1,11 @@
 $(document).ready(function () {
+  // periodically check for server status updates
   $('.serverItem').each(function() {
     setInterval(updateServer, 5000, $(this));
   });
+
+  // set the serverName input field to check if the server exists
+  $('input#serverName').on('change', checkServerExists);
 });
 
 function updateServer(elem) {
@@ -10,3 +14,16 @@ function updateServer(elem) {
     elem.children('.serverState').eq(0).text(data.state);
   });
 }
+
+function checkServerExists() {
+  $.get('/server/' + $(this).val() + '/status', function(data, state) {
+    if (data.exists) {
+      $('input#createSubmit').prop('disabled', true);
+      alert('That server name is already used; please use another name!');
+    } else {
+      if ($('input#createSubmit').prop('disabled')) {
+        $('input#createSubmit').prop('disabled', false);
+      }
+    }
+  });
+}