JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.0.4/angular.min.js"></script>
<div ng-app="myApp" ng-controller="MyCtrl">
    <select ng-model="periodRangeModel" ng-options="item for item in items"></select>
    <div ng-switch on="periodRangeModel">
        <span ng-switch-when="Month"><period-selector items="monthOptions" ng-model="periodModel.value"></period-selector></span>
        <span ng-switch-when="Quarter"><period-selector items="quarterOptions" ng-model="periodModel.value"></period-selector></span>
        <br>
    </div>
    Model: {{periodModel.value}} (this is supposed to change)
</div>

JavaScript

angular.module('myApp', [])
.controller("MyCtrl", function($scope) {
    $scope.items = ['Month', 'Quarter'];
    $scope.periodRangeModel = "Month";
    $scope.quarterOptions = ["Jan-Mar", "Apr-Jun", "Jul-Sept", "Oct-Dec"];
    $scope.monthOptions = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
    $scope.periodModel = {
        value: $scope.monthOptions[0]
    };
})
.directive('periodSelector', function() {
    return {
        restrict: 'E',
        replace: true,
        scope: { items: '=', ngModel: '='},
        template: "<span><select ng-options='period for period in items' ng-model='ngModel'></select></span>"
    }
});