JAVASCRIPT

AngularJS - get previous selected option after ng-click on a ng-repeat

angular.module('myApp', [])
  .controller('myCtrl', ['$scope', function($scope) {
    let selHistory = []
    $scope.selectThing = "val2"
    $scope.recVal = function() {
      if (selHistory.length === 0 || selHistory[selHistory.length - 1] !== $scope.selectThing)
        selHistory.push($scope.selectThing)

      console.log("The history of selections: ", selHistory);
    }
    $scope.recVal(); // push our intiial variable in there

    $scope.revert = function() {
      if (selHistory.length > 0) {
        selHistory.pop();
        $scope.selectThing = selHistory[selHistory.length - 1]
        console.log("The history of selections: ", selHistory);
      }
    }
  }]);
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.7.5/angular.min.js"></script>
<div ng-app="myApp" ng-controller="myCtrl">
  <select ng-change="recVal()" ng-model="selectThing">
    <option value='val1'>1</option>
    <option value='val2'>2</option>
    <option value='val3'>3</option>
  </select>
  <button ng-click='revert()'>Revert</button>
</div>