Javascript 向AngularJS中的按钮添加默认值

我有一个按钮，我想把正常是这个按钮的默认值。我已将ng swich default更改为normal，但它无法在下拉列表中捕获normal中的数据。它只显示字母。我怎样才能用AngularJS做到这一点？我从来没有像以前那样用过它。以下代码：

 <span class="priority-select btn-group" dropdown>
    <button
        type="button"
        class="btn btn-default dropdown-toggle"
        dropdown-toggle>
        <img
            ng-if="form.priority === undefined"
            src="images/task_approval/priority/priority-create.png"
            alt="priority"/>
        <img
            ng-if="form.priority !== undefined"
            ng-src="images/task_approval/priority/{{form.priority}}.png"
            alt="priority"/>
        <span ng-switch="form.priority">
            <span
                ng-switch-when="high"
                class="btn-text"
                translate>High
            </span>
            <span
                ng-switch-when="normal"
                class="btn-text"
                translate>Normal
            </span>
            <span
                ng-switch-when="low"
                class="btn-text"
                translate>Low
            </span>
            <span
                ng-switch-default
                class="btn-text"
                translate>Priority
            </span>
        </span>
    </button>
    <ul class="dropdown-menu" role="menu">
        <li>
            <a ng-click="set_priority('high')">
                <img src="images/task_approval/priority/high.png" alt="high"/>
                <span translate>High</span>
            </a>
        </li>
        <li>
            <a ng-click="set_priority('normal')">
                <img src="images/task_approval/priority/normal.png" alt="normal"/>
                <span translate>Normal</span>
            </a>
        </li>
        <li>
            <a ng-click="set_priority('low')">
                <img src="images/task_approval/priority/low.png" alt="low"/>
                <span translate>Low</span>
            </a>
        </li>
    </ul>
</span>

高的
典型的
低的
优先事项


高的


典型的


低的

必须声明set_priority（）函数，并使用参数更改form.priority值

或

您可以在ng内更改，单击“a”标记。 大概是这样的： ng单击“formPriority='high'”

然后

ng开关=“formPriority”

高的
典型的
低的
优先事项


高的


典型的


低的

我不知道如何更改它。你能给我看看样品吗？对不起，不行。该按钮默认使用图像，无法从“正常”下拉列表中捕获数据@a、 英国

<span class="priority-select btn-group" dropdown>
    <button ng-init='formPriority="normal"'
        type="button"
        class="btn btn-default dropdown-toggle"
        dropdown-toggle>
        <img
            ng-if="formPriority == undefined"
            src="images/task_approval/priority/priority-create.png"
            alt="priority"/>
        <img
            ng-if="formPriority != undefined"
            ng-src="images/task_approval/priority/{{formPriority}}.png"
            alt="priority"/>
        <span ng-switch="formPriority">
            <span
                ng-switch-when="high"
                class="btn-text"
                translate>High
            </span>
            <span
                ng-switch-when="normal"
                class="btn-text"
                translate>Normal
            </span>
            <span
                ng-switch-when="low"
                class="btn-text"
                translate>Low
            </span>
            <span
                ng-switch-default
                class="btn-text"
                translate>Priority
            </span>
        </span>
    </button>
    <ul class="dropdown-menu" role="menu">
        <li>
            <a ng-click='formPriority="high"'>
                <img src="images/task_approval/priority/high.png" alt="high"/>
                <span translate>High</span>
            </a>
        </li>
        <li>
            <a ng-click='formPriority="normal"'>
                <img src="images/task_approval/priority/normal.png" alt="normal"/>
                <span translate>Normal</span>
            </a>
        </li>
        <li>
            <a ng-click='formPriority="low"'>
                <img src="images/task_approval/priority/low.png" alt="low"/>
                <span translate>Low</span>
            </a>
        </li>
    </ul>
</span>