JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.1.4/angular.js"></script>
<div ng-app='TestApp' ng-controller="TestCtrl">   
    1. Updates the noteMatrix in the controller correctly, but produces errors in the javascript console :(
    <table>
        <thead>
            <tr>
                <th>--</th>
                <th ng-repeat="no in machine.noteMatrix[0]">{{$index+1}}</th>
            </tr>
        </thead>
        <tbody>
            <tr ng-repeat="track in machine.noteMatrix">
                <td>--</td>                
                <td ng-repeat="step in track">                    
                    <input type="checkbox" ng-model="track[$index]"> {{step}}
                </td>
            </tr>
        </tbody>
    </table>
    <br>
    2. Produces no errors, but doesn't update the noteMatrix in the controller correctly :'(
    <table>
        <thead>
            <tr>
                <th>--</th>
                <th ng-repeat="no in machine.noteMatrix[0]">{{$index+1}}</th>
            </tr>
        </thead>
        <tbody>
            <tr ng-repeat="track in machine.noteMatrix">
                <td>--</td>                
                <td ng-repeat="step in track">                    
                    <input type="checkbox" ng-model="step"> {{step}}
                </td>
            </tr>
        </tbody>
    </table>
        <button ng-click="printMatrix()">Show Matrix!</button>        
</div>

JavaScript

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

mod.controller('TestCtrl', function ($scope) {        
    var machine = {};
    machine.noteMatrix = [
        [false, false, false],
        [false, true, false],
        [false, false, false]
    ];

    $scope.machine = machine;
    
    $scope.printMatrix = function() {
        var out = '';
        
        for(i = 0; i < 3;i++) {
            out += i+ ": ";
            for(j = 0; j < 3; j++) {
                out += machine.noteMatrix[i][j] + " ";
            }
            out += "\r\n";
        }
        
        alert(out);
    };
    
    
    
});