Detect use of Android back button using JavaScript

Question

My site has breadcrumbs which highlight which stage in a process the user has reached. The breadcrumbs rely on the browser history to tell which stage should be highlighted when

Answer 1

You can put check on inside onBackPressed method of the activity and before calling super.onBackPressed(); trigger the method to call javascript method.

for e.g:

override fun onBackPressed() {
    if (handleBackPress) {
        myWebView.loadUrl("javascript:backButtonPressed()")
    }else {
        super.onBackPressed()
    }
}

in the above example if handleBackPress boolean variable is true, then it will try to call backButtonPressed() method of javascript file in the webview.

Let me know if you need any explanation or help.

Answer 2

1. Use popstate event.

https://developer.mozilla.org/en-US/docs/Web/Events/popstate

window.onpopstate = function(e) { 
   updateBreadCrumbObservable();
};

2. Use onhashchange event.

window.onhashchange = function(e) {
   updateBreadCrumbObservable();
}

You can use event argument to get more description about the event fired.