ionic 4 prevent/disable device hardware backbutton

initializeApp() {
    this.platform.ready().then(() => {
      this.platform.backButton.subscribeWithPriority(9999, () => {
        document.addEventListener('backbutton', function (event) {
          event.preventDefault();
          event.stopPropagation();
          console.log('hello');
        }, false);
      });
      this.statusBar.styleDefault();
    });
  }

I found out how to undo it (give back button previous functionality):

Your observer is pushed to the this.platform.backButton.observers array. So you just have to pop the last element of the list:

this.platform.backButton.observers.pop();

Hope it helps somebody.

05-02-2020

This works for me.

app.component.ts

  

async initializeApp(): Promise<void> {
    await this.platform.ready();
   
    this.platform.backButton.subscribeWithPriority(1, () => { // to disable hardware back button on whole app
    });

  }