如何在ui-select下复制标签文本

<ui-select ng-model="selectedItem">
  <ui-select-match>{{$select.selected.label}}</ui-select-match>
  <ui-select-choices repeat="item in items">
    <div ng-bind-html="item.label | highlight: $select.search"></div>
  </ui-select-choices>
</ui-select>

$scope.copyLabel = function() {
  if ($scope.selectedItem) {
    var tempInput = document.createElement("input");
    tempInput.value = $scope.selectedItem.label;
    document.body.appendChild(tempInput);
    tempInput.select();
    document.execCommand("copy");
    document.body.removeChild(tempInput);
  }
};

<button ng-click="copyLabel()">复制标签文本</button>