Add or remove column not working in handsontable

I'm experimenting with Handsontable add and remove column feature. But it is not working.

Here is my code :-

My index.html

<!DOCTYPE html>
<html ng-app="app">
    <head>
        <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.6.5/angular.js"></script>

        <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/handsontable/0.35.0/handsontable.full.js"></script>
        <!--<link rel="stylesheet" type="text/css" href="css/style.css">-->
        <script type="text/javascript" src="js/app.js"></script>
        <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/handsontable/0.35.0/handsontable.full.css">
        <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/ngHandsontable/0.13.0/ngHandsontable.js"></script>
        <!--<script type="text/javascript" src="data/datafactory.js"></script>-->
    </head>


    <body MainCtrl as ctrl>

<hot-table col-headers="true" datarows="ctrl.data">
    <hot-column ng-repeat="column in ctrl.columns" data="{{column.data}}" title="column.title" read-only="column.readOnly"></hot-column>
</hot-table>

<button ng-click="ctrl.addColumn()">Add column</button>
<button ng-click="ctrl.removeColumn()">Remove column</button>

    </body>

</html>

My app.js

 function MainCtrl() {
    var items = [[]];

    this.data = items;
    this.columns = [
      {
        data: 'id',
        title: 'ID',
        readOnly: true
      },
      {
        data: 'price',
        title: 'Price',
        readOnly: false
      }
    ];

    this.addColumn = function() {
      this.columns.push({});
    };
    this.removeColumn = function() {
      this.columns.pop();
    };
  }

  angular
  .module('app', ['ngHandsontable'])
  .controller('MainCtrl', MainCtrl);

MainCtrl.$inject = [];

When I run the code it doesn't work and doesn't allow to add or remove column. I am new to both angular and front-end design. So seeking help here.

Solution

I believe you need to order your <script> tags properly - your code should go at the end (I imagine your code is in js/app.js):

    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.6.5/angular.js"></script>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/handsontable/0.35.0/handsontable.full.js"></script>
    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/handsontable/0.35.0/handsontable.full.css">
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/ngHandsontable/0.13.0/ngHandsontable.js"></script>
    <script type="text/javascript" src="js/app.js"></script>

Also try using arrow functions where you can instead of function()... Or set up:

let ctrl = this;

You may get in trouble using this the way you do it. Scope of this can and sometimes will change.

Here's example of your code working in JS fiddle: https://jsfiddle.net/pegla/b6rj93cg/2/