javascript - select box default value

Question

This is the html part of select

<select class="form-control w-searchbar-select" ng-model="aa" ng-init="aa='请选择设备状态'" >
   <option ng-repeat="data in  ProcedureList" value="{{$index}}">{{data}}</option>
</select>

The following is the equipmentProcedureList part defined

$scope.equipmentProcedureList = ["请选择设备状态", "注册", "使用中", "故障", "报废"];

The effect of the current writing method on the page is:
No items are selected in the select box and it is blank.
However, if the value="{{$index}}" in option is removed, it will be displayed normally.
Seek the guidance of the great God

Answer 1

The desired page effect is to select "Please select device status" by default, and the value of the remaining items is $index. Finally, ng-repeat is used to implement the above functions.
$scope.equipmentProcedureList = ["Please select device status", "Registered", "In use", "Fault", "Scrap"];

The above are the drop-down options of select, predefined.

$scope.aa="请选择设备状态";

Specify the items selected by default here

<select class="form-control w-searchbar-select" ng-model="aa" >
   <option value="请选择设备状态"></option>
   <option ng-repeat="data in  equipmentProcedureList" value="{{$index}}">{{data}}</option>
</select

This is the HTML part

Answer 2

angularJS recommends using ng-options to create drop-down menus

<select ng-model="aa" ng-options="y for (x, y) in ProcedureList"></select>

$scope.ProcedureList = ["请选择设备状态", "注册", "使用中", "故障", "报废"];

//我一般使用下面这样初始化不用ng-init,这样我觉得好改一点，想初始化几就写数组的索引
$scope.aa = $scope.ProcedureList[0];

Answer 3

The value of value in option is a number, and when initialized, value='Please select device status', there is no corresponding display value with this value..