i have a problem to get the value of a selected value from a dropdownlist 

my code jquery is : `$( "#statistic_commune option:selected" ).text();`

this code work when i use just html like : `select.form-control name="statistic[state]" id="statistic_commune "`

but it doesn't work when i use : rails tag like `= towns_select_tag(:statistic, :commune, {include_blank: true}, {class: 'form-control'},{id: 'statistic_commune'})`
help please