angular.js - When using $watch to monitor select in angular, there will always be an extra blank option. After the first selection, the blank option disappears. Has anyone encountered the same situation?

Question

 <select name="" id="" ng-model="currenttype">
        <option value="null">---请选择---</option>
        <option  ng-repeat="r in roles" value={{r.emp_id}}>{{r.emp_name}}</option>
        </select>
        
        $scope.currenttype="";
        $scope.$watch('currenttype',function(){
                alert($scope.currenttype);
        })

    
   ![图片描述][1]

Answer 1

That’s because it’s executing repeat 的时候 ng-model 尚未有值 ,你可以发现空白的那个option中会有一个 value="?"
给一个初始化话的值就好了
$scope.currenttype=$scope.roles[0];
That’s it

Answer 2

model is not initialized