JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://code.angularjs.org/1.0.1/angular-1.0.1.js"></script>
<div ng-app ng-controller="TodoCtrl">
    <h2>This example doesn't work, it demonstrates functionality I'd like to have</h2>            
    <ul>
    <li ng-repeat="todo in todos">
        <input type="checkbox" ng-model="todo.done">
        {{todo.text}}</li>
    </ul>

</div>

JavaScript

function TodoCtrl($scope) {
   
    $scope.todos = [
        {done: true, text: "foo"},
        {done: false, text: "bar"}
    ];
    
    // change on part of the array doesn't work   
    $scope.$watch('todos[$index]',
        function(newval, oldval, scope, index) {
            console.log(
                "todo with following text changed:",
                $scope.todos[index].text
            );
    }, true);
 
}