How can I preload a Dropdown List with multiple values from a script?

In the documentation for AEM form development here: https://dev.day.com/docs/en/cq/5-5/developing/developing-forms.html#Preloading%20Form%20Fields%20with%20Multiple%20Values

In step 2 of the Example - Preloading A Dropdown List with Multiple Values, its said that content can be imported using a script.  How can I do this, and are there any examples?

Thanks!