K.Rice K.Rice -4 years ago 370
TypeScript Question

Ionic 2 prevent hardware back button default

How can I prevent default navigation when pressing hardware back button? I've tried

registerBackButtonAction
, but then it overwrites behavior of back button in every page which I don't want.

This didn't help either.

document.addEventListener("backbutton", (event) => {
event.preventDefault();
}, false);

Answer Source

As you can see in Ionic docs registerBackButtonAction returns a function:

A function that, when called, will unregister its back button action.

So you can use that function to restore the default behavior when leaving the page, like this:

import { Component} from '@angular/core';

@Component({
    selector: 'page-home',
    templateUrl: 'home.html'
})
export class HomePage {

    // Property used to store the callback of the event handler to unsubscribe to it when leaving this page
    public unregisterBackButtonAction: any;

    constructor(...) { ... }

    ionViewDidEnter() {
        this.initializeBackButtonCustomHandler();
    }

    ionViewWillLeave() {
        // Unregister the custom back button action for this page
        this.unregisterBackButtonAction && this.unregisterBackButtonAction();
    }

    public initializeBackButtonCustomHandler(): void {
        this.unregisterBackButtonAction = this.platform.registerBackButtonAction(() => {
            this.customHandleBackButton();
        }, 10);
    }

    private customHandleBackButton(): void {
        // do what you need to do here ...
    }
}

So as you can see, the key is to store the callback of the registerBackButtonAction method and use it later when leaving the page (or when you want to restore the default behavior):

this.unregisterBackButtonAction = this.platform.registerBackButtonAction(() => {
    this.customHandleBackButton();
}, 10);
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