Adding/remove widget along with resize not working

I have used basic gridster code and then I have declared functions to add and remove widgets by button It works fine But when I add the resize functionality to the above code none of it works(I mean resize,add and delete widgets)

My js code is following

<script type="text/javascript">
    var gridster;

    gridster = $(".gridster ul").gridster({
        widget_base_dimensions: [100, 100],
        widget_margins: [5, 5],
        helper: 'clone',
        resize: {
            enabled: true
        }           


    }).data('gridster');



$(document).on( "click",".delete-button", function() {
var gridster = $(".gridster ul").gridster().data('gridster');
gridster.remove_widget($(this).parent());
});



$(document).on( "click",".add-button", function() {
var gridster = $(".gridster ul").gridster().data('gridster');      
gridster.add_widget('<li><button class="delete-button" style="float: 
right;">-</button><h3></h3></li>',1,1);
});

Above code is not working

The working code is just not having this in it

resize: {
        enabled: true
    }

Solution

Referring to the solution here, have updated your code with the resizable()

Also added the css file jquery.gridster.css.

$(function() {
  var gridster;
  var grid_size = 100;
  var grid_margin = 5;
  gridster = $(".gridster ul").gridster({
    widget_base_dimensions: [100, 100],
    widget_margins: [5, 5],
    helper: 'clone',
    resize: {
      enabled: true
    }


  }).data('gridster');



  $(document).on("click", ".delete-button", function() {
    var gridster = $(".gridster ul").gridster().data('gridster');
    gridster.remove_widget($(this).parent());

  });



  $(document).on("click", ".add-button", function() {
    gridster
      .add_widget('<li><button class="delete-button" style="float: right;">-</button><h3></h3></li>', 1, 1);
    gridster.resizable({
      grid: [grid_size + (grid_margin * 2), grid_size + (grid_margin * 2)],
      animate: false,
      minWidth: grid_size,
      minHeight: grid_size,
      containment: '#layouts_grid ul',
      autoHide: true,
      stop: function(event, ui) {
        var resized = $(this);
        setTimeout(function() {
          resizeBlock(resized);
        }, 300);
      }
    });
  });
})

<link href="https://cdnjs.cloudflare.com/ajax/libs/jquery.gridster/0.5.6/jquery.gridster.css" rel="stylesheet"/>
<link href="https://dsmorse.github.io/gridster.js/demos/assets/css/demo.css" rel="stylesheet"/>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery.gridster/0.5.6/jquery.gridster.min.js"></script>
<h1>Add and Remove Widget Dynamically</h1>

<p>When you remove a widget,the widget below it will always remain in the same column.Widget from next column wont come in place of widget removed.Gridster is designed that way</p>
<a href="https://github.com/ducksboard/gridster.js/issues/338" target="_blank"> Click to know more</a>


<div class="gridster">
  <ul>
    <li data-row="1" data-col="1" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>1</h3>
    </li>
    <li data-row="1" data-col="2" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>2</h3>
    </li>
    <li data-row="1" data-col="3" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>3</h3>
    </li>
    <li data-row="1" data-col="4" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>4</h3>
    </li>
    <li data-row="2" data-col="1" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>5</h3>
    </li>
    <li data-row="2" data-col="2" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>6</h3>
    </li>
    <li data-row="2" data-col="3" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>7</h3>
    </li>
    <li data-row="2" data-col="4" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>8</h3>
    </li>
    <li data-row="3" data-col="1" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>9</h3>
    </li>
    <li data-row="3" data-col="2" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>10</h3>
    </li>
    <li data-row="3" data-col="3" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>11</h3>
    </li>
    <li data-row="3" data-col="4" data-sizex="1" data-sizey="1"><button class="delete-button" style="float: right;">-</button>
      <h3>12</h3>
    </li>



</div>


<button class="add-button" style="float:top;">Add Widget</button>