title: Reset select to default value with AngularJS
body: <p>I have a following question for AngularJS. I have a 
  select with options created with ngOptions. I want to 
  set selected option back to default option. I tried to 
  delete model variable e.g: </p>
  
  <pre><code>if(angular.isDefined($scope.first)){
      delete $scope.first;
  }
  </code></pre>
  
  <p>But this not working. Here is my html. </p>
  
  <pre><code>    &lt;div ng-app="app"&gt;
          &lt;div ng-controller="testCtrl"&gt;
              &lt;select data-ng-model="first"  data-ng-options="item.name for item in selectContent" required="required"&gt;
                &lt;option value="" style="display: none;"&gt;-- select --&lt;/option&gt;
              &lt;/select&gt;
              {{first.value}}
  &lt;hr/&gt;
          &lt;input type="button" value="reset dropdown" data-ng-click="resetDropDown()"/&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  </code></pre>
  
  <p>And here is my JavaScript code:</p>
  
  <pre><code>angular.module('app', []).controller('testCtrl', function ($scope) {
      $scope.selectContent = [
          {
              name: "first",
              value: "1"
          },
          {
              name: "second",
              value: "2"
          }
      ];
  
      $scope.resetDropDown = function() {
          if(angular.isDefined($scope.first)){
              delete $scope.first;
          }
      }
  });
  </code></pre>
  
  <p>Here is working jsfiddle: </p>
  
  <p><a href="http://jsfiddle.net/zono/rzJ2w/">http://jsfiddle.net/zono/rzJ2w/</a></p>
  
  <p>How I can solve this problem? </p>
  
  <p>Best regards. </p>