Selectable Towns

function attachEvents() {
    let content = [];
    let liItems = $('#items li').toArray();
    let btnClicked = $('#showTownsButton');
    $(liItems).on('click', selected);

    function selected() {
        for (town of liItems) {
            if ($(this).attr('data-selected') === "true") {
                $(this).attr('data-selected', false)
                    .removeAttr('id', 'selectedTowns')
                    .css('background-color', '')
                    .map(x => content.pop(x.textContent));
            } else {
                $(this).attr('data-selected', true)
                    .attr('id', 'selectedTowns')
                    .css('background-color', '#DDD')
                    .map(x => content.push(x.textContent));
            }
        }
    }
    $(btnClicked).on('click', btnClickedF);

    function btnClickedF() {
        $('#selectedTowns').text(content.join(', '));
    }
}