var myObject = {
  "myprop1":"value",
  "myprop2":"second",
  "myMethod": function(params) {
    this.myprop1 = params[0];
  }
}
var my_instance = new myObject();
script.log(my_instance.myprop1);
my_instance.mymethod(["test","one","two"]);
script.log(my_instance.myprop1);

When adding a value parameter in a module, only the parameter is saved between sessions/projects. If you want to keep the value content, use setAttribute(“saveValueOnly”,false)

var mycontainer = local.values.addContainer("toto");
var myint1 = mycontainer.addIntParameter("myint", "",1,1,65536);
myint1.setAttribute("saveValueOnly",false);

function getCustomVariablesGroup(name, shortname) {
  var my_group = root.customVariables.getItemWithName(shortname);
  if (my_group.name != shortname) {
    // build a new group
    my_group = root.customVariables.addItem(shortname);
    my_group.setName(name);
  }
  return my_group;
}

/**
 * Set or create then set the custom variable value
 * @param {int} page_id 
 * @param {int} exec_id 
 * @param {int} value 
 * @param {string} type 
 * @param {string} item_nice_name 
 */
function setCustomVariablesValue(page_id, exec_id, value, type, item_nice_name) {
  // build names
  var shortname = "exec"+ page_id+ "_"+ exec_id;
  var name = "Exec "+ page_id+ "_"+ exec_id;
  // get the group
  var my_group = getCustomVariablesGroup(name, shortname);
  // define the item type
  var item_name = type;
  var item_type = "Int";
  var int_max = 100;

  if (["Go", "Stop", "Resume", "Off"].contains(type)) {
    item_type = "Bool";
  }
  // build some names
  var my_value = {};
  var my_value_name = "exec"+ page_id+ "_"+exec_id+ item_name;
  var my_value_nice_name = "Exec "+ page_id+ "_"+ exec_id+ " "+ item_nice_name;

  var my_value_item = my_group.variables.getItemWithName(my_value_name);
  if (my_value_item.name != my_value_name) {
    // create if not exist
    my_value_item = my_group.variables.addItem(item_type+ " Parameter");
    my_value = my_value_item.getChild(my_value_item.name);
    my_value.setName(my_value_nice_name);

    if (["CueMsb", "CueLsb"].contains(type)) {
      int_max = 999;
    }
    if (["Hour", "Minute", "second"].contains(type)) {
      int_max = 60;
    }
    if (!["Go", "Stop", "Resume", "Off"].contains(type)) {
      my_value.setRange(0,int_max);
    }
  }
  else {
    my_value = my_value_item.getChild(my_value_item.name);
  }
  if (["Go", "Stop", "Resume", "Off"].contains(type)) {
    my_value.set(true);
    my_value.set(false);
  }
  else {
    my_value.set(value);
  }
  my_group.variables.reorderItems();
}