How can I check changes in selected options with jQuery?

Question

I want to store a value of the selected option and change it every time when user will change his mind. I used something like $('#selections').val() but first I receive undefined value and nothing happen when certain option is selected.

<select id="selections">
                <option value="0">None</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3">3</option>
                <option value="4">4</option>
                <option value="5">5</option>
                <option value="6">6</option>
                <option value="7">7</option>
                <option value="8">8</option>
                <option value="9">9</option>
                <option value="10">10</option>
              </select>

Answer 1

$("#selections").on('click', function() {
      var value = $(this).val();
      alert(value);
    });

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select id="selections">
  <option value="0">0</option>
  <option value="1">1</option>
  <option value="2">2</option>
</select>

$("#selections").on("change", function() {
    var value = $(this).val();
});