How to sum value of checked changed checkbox jquery?

i have a table, each checkbox contains a value , and i want to sum value of checkbox .Example : Candy and Water is checked : count = 2 , Candy, food and water is checked : count = 5 , checkbox is unchecked : count = 0 . I think i must two event , event of each checkbox (.checkbox1) and event of checkbox (.check_all).

      var count = 0;
            $(".checkbox1").change(function() {
                var table_abc = document.getElementsByClassName("checkbox1");
                for (var i = 0; table_abc[i]; ++i) {
                    if (table_abc[i].checked) {
                        count += table_abc[i].value;
                    }
                }
           });

alert(count);

<table id="div_table" >
<thead>
<tr>
<th><input type="checkbox" class="check_all" id="chk_all" /></th>
<th>Check All</th>
</tr>
</thead>
<tbody>
<tr>
<td><input type="checkbox" class="checkbox1"  id="candy" value="2" /></td>
<td>Candy</td>
</tr>
<tr>
<td><input type="checkbox" class="checkbox1"  id="food" value="3" /></td>
<td>Food</td>
</tr>
<tr>
<td><input type="checkbox" class="checkbox1"  id="water" value="0" /></td>
<td>Water</td>
</tr>
</tbody>
</table>

But it seem not working. Can you tell me how to wrong . Thank guys.