如何对AngularJS生成的选择列表进行预选？

发布时间：2020-12-17 08:34:53 所属栏目：安全来源：网络整理

导读：select ng-model="team.captain" ng-options="player.name for player in team.players"/select 这正确地创建了一个选择列表来选择团队队长。但是，默认情况下选择空白选项。我们如何从列表中预选第一个播放器？ select ng-model="team.captain" ng-options=

<select ng-model="team.captain" ng-options="player.name for player in team.players"></select>

这正确地创建了一个选择列表来选择团队队长。但是，默认情况下选择空白选项。我们如何从列表中预选第一个播放器？

<select ng-model="team.captain" ng-options="player.name for player in team.players" class="ng-pristine ng-valid">
  <option value="0">John</option>
  <option value="1">Bobby</option>
</select>

我试着添加ng-init =“team.captain =’0’”但是没有帮助。

更新显然，这是因为

a value referenced by ng-model doesn’t exist in a set of options passed to ng-options.

资料来源：Why does angularjs include an empty option in select

但是，问题仍然是为什么使用ng-init不工作？

<select ng-init="team.captain='0'" ng-model="team.captain" ng-options="player.name for player in team.players"></select>

这是什么工作：

<select ng-init="team.captain=team.players[0]" 
        ng-model="team.captain" 
        ng-options="player.name for player in team.players"></select>

和什么不工作：

ng-init="team.captain='0'"
ng-init="team.captain='John'"

我的猜测是，Angular超越了简单的值或标签的比较。它可能比较对象引用。

（编辑：李大同）

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