Answers for "find option and set selected jquery"

set select option as selected jquery

$(document).ready(function() {
    $("#gate option[value='Gateway 2']").prop('selected', true);
    // you need to specify id of combo to set right combo, if more than one combo
});

jquery selected option value

let payment_type = $("#olca_form_submit select[name='payment_type']")
      .find(":selected")
      .val();