需要访问下拉的范围，然后应用如下图:

You need to access the scope of the dropdown and then apply it as shown below:

$('button').on('click', function(){
    var newVal = $(this).data('val');
    $('select').val(newVal).change();

    var scope = angular.element($("select")).scope();
    scope.$apply(function(){
        scope.selectValue = newVal;
    });
});