JSFiddle - React, Tailwind, and code Playground
HTML
<body ng-app="myApp">
<div ng-controller="MyController">
<input type="text" ng-model="myVar1" /> {{ myVar1 }}
<br />
<input type="text" ng-model="myVar2" /> {{ myVar2 }}
<br />
{{ myVar3 }}
</div>
</body>
JavaScript
var myApp = angular.module('myApp', []);
myApp.controller('MyController', ['$scope', function($scope){
$scope.myVar3 = $scope.myVar1;
}]);