var context = SP.ClientContext.get_current();
var web = context.get_web();
var list = web.get_lists().getByTitle('List Title');
var itemIds = [1, 2, 56, 90, 108 ];
var items = [];
itemIds.forEach(function(itemId){
    var item = list.getItemById(itemId);
    context.load(item);
    items.push(item);
});
context.executeQueryAsync(
  function() {
     items.forEach(function(item){
        console.log(item.get_item('Title'));
     });
  },
  function(sender,args){
     console.log(args.get_message());
  }
);