Javascript 在angular js中为ng选项选择默认值

我有以下代码：

<select ng-init="state" id="state" ng-model="state"
    ng-options="state for state in states" required>
</select>

这不起作用

如何实现这一点？

您可以添加另一个默认选项，如下所示：

<select ng-init="state" id="state" ng-model="state" ng-options="state for state in states" required>
    <option value="">Select a state</option>
</select>

选择一个状态

此空选项将被选择为默认值

<select ng-init="state" id="state" ng-model="state" ng-options="state for state in states" required>
    <option value="">Select a state</option>
</select>