redmine_qbo/assets/javascripts/application.js

$(function() {
    $("input#issue_customer").autocomplete({
      console.log("input#issue_customer.autocomplete"); 
      source: function (request, response) {
        $.ajax({
            url:  "/filter_vehicles_by_customer",
            type: "GET",
            data: { selected_customer: $("input#issue_customer").val() }
        });
    });
});