select2 set selected option code example
Example 1: select2 preselect option
$('#mySelect2').val('1'); // Select the option with a value of '1'
$('#mySelect2').trigger('change'); // Notify any JS components that the value changed
Example 2: select2 add option
// Set the value, creating a new option if necessary
if ($('#mySelect2').find("option[value='" + data.id + "']").length) {
$('#mySelect2').val(data.id).trigger('change');
} else {
// Create a DOM Option and pre-select by default
var newOption = new Option(data.text, data.id, true, true);
// Append it to the select
$('#mySelect2').append(newOption).trigger('change');
}