jQuery select2

selectjs.txt

/* Dynamically add options to select field */
// Assuming 'custom-select' is the class of select field


<select class="custom-select">
<option value="a">A</option>
<option value="b">B</option>
<option value="c">C</option>
</select>

var mySelect = $(".custom-select").append('<option value="test">Test</option>'); 
mySelect.trigger("change");