JSFiddle - React, Tailwind, and code Playground

HTML

<body ng-app="app" ng-init="value=0">
    <button ng-click="value=1">Set value to 1</button>
    <test-directive activate="value"></test-directive>     
</body>

JavaScript

var app = angular.module('app', []);


app.directive('testDirective', function() {
    return {
        restrict: 'E',
        scope: {
            activate : '='
        },
                
        link: function(scope, elem, attrs, controller) {
            var el = elem[0];
            
            var updateContent = function() {
                el.innerText = 'Activate=' + scope.activate;
            };
                                    
            scope.$watch( 'activate', function(value) {                               
                console.log('Activate=', value);
                if(value === 1) {
                    scope.activate = '0'                    
                }
                updateContent();
            });
        }
    }
});