selectInput Category selection - shiny

Question

I have a selectInput code as like this
selectInput('x4', 'X4', choices = list(
Eastern = c(`New York` = 'NY', `New Jersey` = 'NJ'),
Western = c(`California` = 'CA', `Washington` = 'WA')
), selectize = FALSE)
Is it possible enable section on category, like Eastern, Western. If user selected Eastern both values have to load ( New Jersey and New York). Is it possible ?

Answer 1

library(shiny)
onInitialize <- "
function(){
var select = this.$input[0];
this.$dropdown_content.on('mousedown', function(e){
e.preventDefault();
return false;
}).on('click', '.optgroup-header', function(e){
var options = $(this).parent().find('.option');
var items = [];
options.each(function(i, opt){items.push($(opt).data('value'));});
var selections = select.selectize.items;
select.selectize.setValue(items.concat(selections));
});
}
"
shinyApp(
ui = fluidPage(
selectizeInput("state", "Choose a state:",
list(`East Coast` = list("NY", "NJ", "CT"),
`West Coast` = list("WA", "OR", "CA"),
`Midwest` = list("MN", "WI", "IA")),
multiple = TRUE,
options = list(
onInitialize = I(onInitialize)
)
)
),
server = function(input, output){}
)