JSFiddle - React, Tailwind, and code Playground

HTML

<body ng-app="demoApp">
    <div ng-controller="DemoController">

        <div>

            <select ng-model="firstSelect"
                ng-options="opt as opt.label for opt in options">
            </select>
<br><br>
<div ng-if="firstSelect.value == '4'"  ng-model="secondSelect">
            <select  
                ng-options="opt as opt.name for opt in captions">
            </select><br>
             <select   ng-model="secondSelect"
                ng-options="opt1 as opt1.name for opt1 in captions1">
            </select><br>
            </div>
            <select  ng-if="firstSelect.value == '3'" ng-model="secondSelect"
                ng-options="opt as opt.name for opt in captions1">
            </select><br>
        </div>

    </div>
</body>

JavaScript

angular.module('demoApp', []).controller('DemoController', function($scope) {
//my first drop down loads with the page
  $scope.options = [
  
    { label: 'three', value: 3 },
    { label: 'four', value: 4 }
 
  ];       
  $scope.firstSelect = $scope.options[3];  
   
//the second drop down loads after the first makes a selection. In the real code I am populating the second from localstorage, but once it's assigned its default value I cannot change it.    
    var init = function(){
       //depends on what was selected in first select
        $scope.captions = [
           { name: 'A', value: 'a' },
           { name: 'B', value: 'b' },
           { name: 'C', value: 'c' },
           { name: 'D', value: 'd' },
           { name: 'E', value: 'e' }
       ]; 
            $scope.captions1 = [
           { name: 'A', value: 'a' },
           { name: 'B', value: 'b' }
           
       ]; 
        $scope.secondSelect = $scope.captions[1];
        $scope.captions1 = [
           { name: 'Aq', value: 'aq' },
           { name: 'B', value: 'b' },
           { name: 'C', value: 'c' },
           { name: 'D', value: 'd' },
           { name: 'E', value: 'e' }
       ]; 
        $scope.secondSelect = $scope.captions[1];
    }   
    init();
    
});