MarionetteJS: Application Regions vs. Layouts [duplicate] - backbone.js

Question

This question already has an answer here:
What to use since Marionette Application Regions are deprecated
(1 answer)
Closed 6 years ago.
I was reading the documentation of the latest version (2.3.0) and it is saying that Application Regions are now deprecated.
Application Regions
Warning: deprecated This feature is deprecated. Instead of using the
Application as the root of your view tree, you should use a Layout
View. To scope your Layout View to the entire document, you could set
its el to 'body'. This might look something like the following: var
RootView = Marionette.LayoutView.extend({ el: 'body' });
In most of the tutorials, including David Sulc's book Backbone Marionette: A Gentle Introduction it uses the following code snippet to add regions to an application.
Instead of the following example below, which uses addRegions, what should I be doing instead?
i.e.
var ContactManager = new Marionette.Application({});
ContactManager.addRegions({
mainRegion: "#main-region"
});
var ContactView = Marionette.ItemView.extend({
template: "#whatever",
ui: {
button: ".button".
},
events: {
"click #ui.button": "click",
},
click: function () {
console.log("do stuff here...");
}
});
ContactManager.on("start", function () {
var contactView = new ContactView({
model: someModel
});
ContactManager.mainRegion.show(contactView);
});

Answer 1

Use a layoutview instead.
You could do for example:
var ContactManager = new Marionette.Application({});
var LayoutView = Backbone.Marionette.LayoutView.extend({
template: "#layout-view-template",
regions: {
menu: "#menu",
content: "#content"
}
});
ContactManager.layout_view = new LayoutView();
ContactManager.layout_view.render();
I never actually add regions to my app object directly.