Ionic 2 backbutton Event Listener

Ionic Framework ionic-v3
1

I want to achieve the click Back button, pop-up Toast box，Not quit
document.addEventListener(“backbutton”, () => {
Toast.show(“I’m a toast”, “5000”, “center”).subscribe(
toast => {
console.log(toast);
}
);
// console.log(‘close’);
},false);

But actually，Quit App first, and then pop box Toast

2

this is works in ionic 2??
and r u have any code for device back button pressed event?
if u have please share with me.