Here it is explained how to get your select list to show only options containing text which is entered in a long select list to make it easier to find the wanted option in the list.

To achieve so, go to your form's Advanced properties > More options > Scripts and in the Initialization script set Type to Custom.

In the code area below that appears, put the following code:

function ff_FORMNAME_init()
{

jQuery('[name="ff_nm_searchfiledname[]"]').keydown(function() {
    jQuery('[name="ff_nm_selectlistname[]"] option').prop('hidden', false);
    jQuery('[name="ff_nm_selectlistname[]"] option').not(jQuery('[name="ff_nm_selectlistname[]"] option:icontains('+ff_getElementByName('searchfiledname').value+')')).prop('hidden', true);

});


} // ff_FORMNAME_init

jQuery.expr[':'].icontains = function(a, i, m) {
  return jQuery(a).text().toUpperCase()
      .indexOf(m[3].toUpperCase()) >= 0;
};

 

NOTE: In the code above you have to replace FORMNAME with the Name of your form. Furthermore, replace every instance of "searchfieldname" with the textfield in your form and every instance of "selectlistname" with the Name of the select list which you wish to search through.

This search will be case insensitive and change in list will be applied as text is entered in the textfield.