CODE EXAMPLE FOR JAVASCRIPT

jquery detect select change

Script/Jquery code
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$('#selectChange').on('change', function() {
  alert( this.value );
});


HTML PART
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<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<select id="selectChange">
    <option value="1">One</option>
    <option value="2">Two</option>
</select>