selectAll.change(function () {

langs.prop('checked', selectAll.prop('checked'));

selectAllLabel.toggle();

deselectAllLabel.toggle();

});

invertSelect.click(function() {

langs.prop('checked', (index, value) => !value);

langs.change();

});

langs.change(function() {

var checkedLangs = langs.filter(function() {

return $(this).prop('checked');

});

if (checkedLangs.length === langs.length) {

selectAll.prop('checked', true);

selectAll.change();

} else if (checkedLangs.length == 0) {

selectAll.prop('checked', false);

selectAll.change();

}

});