ionic 4 back button code example
Example 1: back button ionic
<ion-header>
<ion-toolbar>
<ion-buttons slot="start">
<ion-back-button></ion-back-button>
</ion-buttons>
</ion-toolbar>
</ion-header>
Example 2: ionic how to block back button
this.platform.backButton.subscribe(() => {
// do something here
});