Getting val() of last checkbox checked by a user [duplicate]

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• How to limit the number of selected checkboxes? 12 answers

I am building an application that allows users to choose pizza toppings by checking/unchecking checkboxes. The maximum I would like them to be able to select is 3 checkboxes. Once they select 4, I would like to send an alert to the user and deselect the last_checked checkbox. I have tried the following code to access the value of the most recent checked checkbox:

$("#Pizza #id_toppings").change(function() {
    var last_checked = $("#Pizza #id_toppings input[name='toppings']:checked").val()
    alert("The checkbox: '" + last_checked + "' changed");
});

Unfortunately, this only returns the value of the lowest checked box. Any ideas how I can get it to return the last_checked box? Example form is below.

<form action="/cart/" method="post" id="Pizza">
    <input type="hidden" name="csrfmiddlewaretoken" value="hmgXKE0ximQjeAvhcSpLPa4WvL7dtUHW76D41WAgxMyzoBzTpzjeAMVuA99P3kSD">
    <input type="hidden" value="Pizza" name="menu_item" id="menu_item" />

    <p><label for="id_style">Style:</label> <select name="style" required id="id_style">
  <option value="" selected>---------</option>

  <option value="1">Regular</option>

  <option value="2">Sicilian</option>

</select></p>
<p><label for="id_size">Size:</label> <select name="size" required id="id_size">
  <option value="" selected>---------</option>

  <option value="1">Small</option>

  <option value="2">Large</option>

</select></p>
<p><label for="id_is_special">Gluten Free Dough:</label> <input type="checkbox" name="is_special" id="id_is_special"></p>
<p><label for="id_num_toppings">Number of Toppings:</label> <input type="number" name="num_toppings" required id="id_num_toppings"></p>
<p><label>Toppings:</label> <ul id="id_toppings">
    <li><label for="id_toppings_0"><input type="checkbox" name="toppings" value="1" id="id_toppings_0">
 Pepperoni</label>

</li>
    <li><label for="id_toppings_1"><input type="checkbox" name="toppings" value="2" id="id_toppings_1">
 Sausage</label>

</li>
    <li><label for="id_toppings_2"><input type="checkbox" name="toppings" value="3" id="id_toppings_2">
 Mushrooms</label>

</li>
    <li><label for="id_toppings_3"><input type="checkbox" name="toppings" value="4" id="id_toppings_3">
 Onions</label>

</li>
    <li><label for="id_toppings_4"><input type="checkbox" name="toppings" value="5" id="id_toppings_4">
 Ham</label>

</li>
    <li><label for="id_toppings_5"><input type="checkbox" name="toppings" value="6" id="id_toppings_5">
 Canadian Bacon</label>

</li>
    <li><label for="id_toppings_6"><input type="checkbox" name="toppings" value="7" id="id_toppings_6">
 Pineapple</label>

</li>
</ul></p>

    <h5 id='price_indicator'>Price: $--.--</h5>
    <input type="submit" value="Add Pizza to Cart" />
</form>