angularjs的if、else语句

<div ng-controller="ONUconfigureCtrl" style="padding: 20px 0px 5px 0px;" class="well">
<div ng-hide="telnetIsOn" class="row" style="height:1000px">
<div class="span5">
<div class="row">
<label class="span2">设备型号</label>
<select ng-change="Myapp(myOption)" ng-model="myOption" ng-init="myOption='MA5626'">
<option>MA5626</option>
<option>MA5620</option>
<option >MA5620E</option>
<option >F820</option>an
<option >F821</option>
</select>
</div>
<div class="row">
<label class="span2">OLT 类型</label>
<select ng-model="OLTtype" class="span2" ng-options=
4000
"m.option for m in ONUtype.list">
<option value="">请选择</option>
</select>
</div>
<div class="row">
<label class="span2" for="OLTIP">OLT IP</label>
<input class="span2" required type="text" name="OLTIP" ng-model="OLTIP" id="OLTIP" placeholder="0.0.0.0">
</div>
<div class="row">
<label class="span2" for="SLOT">槽位</label>
<input class="span1" required type="number" name="SLOT" ng-model="SLOT" id="SLOT">
</div>

$scope.isShow = true;   //事件初始化
$scope.a = true;
$scope.b = true;
$scope.Myapp = function(obj){     //传递参数
if(obj == 'MA5626'){          //定义相应变量
$scope.isShow = true;
$scope.a = true;
$scope.b = true;
}
else if(obj == 'MA5620'){
$scope.isShow = false;
$scope.a = true;
$scope.b = false;
}
else {
$scope.isShow = false;
$scope.a = false;
$scope.b = false;
}
};