prompt user on backspace and browser backbutton in gwt

Question

I have two classes when navigating from one class to another created history. Now, I want to prompt the user by a confirm whether user wants to leave the page or not.Till no

Answer 1

I have got this in JSNI, But its also not working in browser back button..

public native void call()/*-{

    $wnd.onkeypress = GetChar;

     function GetChar (event)
     {
        var key = event.keyCode;

        var bb = event.target.nodeName;

             if(key==8 && bb=="BODY")
                {
                    var x= window.confirm("Are you sureyou want to leave the page");

                    if (x==true)
                            {
                                window.history.back();
                            }
                    else if(x==false)
                            {

                                return false;
                            }
                }
        }                   
}-*/;

Answer 2

Have you tried with History.addValueChangeHandler which listens for changes in the browser's history stack?

---

-- EDIT --

Below code is working fine for Backspace key in Firefox, Chrome as well as IE9.

Note: Please test it for other browsers also and let me know if there is any issue.

    Event.addNativePreviewHandler(new Event.NativePreviewHandler() {

        @Override
        public void onPreviewNativeEvent(final NativePreviewEvent event) {
            boolean isFirefox = checkBrowser("Firefox");
            if ((isFirefox && event.getTypeInt() == Event.ONKEYPRESS)
                    || (!isFirefox && event.getTypeInt() == Event.ONKEYDOWN)) {
                if (event.getNativeEvent().getKeyCode() == KeyCodes.KEY_BACKSPACE) {
                    Element element = Element.as(event.getNativeEvent().getEventTarget());

                    String tagName = element.getTagName();

                    System.out.println(tagName);

                    if (!tagName.equalsIgnoreCase("INPUT")
                            && !tagName.equalsIgnoreCase("TEXTAREA")) {

                        boolean result = Window.confirm("Are you sure?");
                        if (!result) {
                            event.cancel();
                        }
                    }
                }
            }
        }
    });

    if (checkBrowser("Firefox")) {
        DOM.sinkEvents(RootPanel.get().getElement(), Event.ONKEYPRESS);
    } else {
        DOM.sinkEvents(RootPanel.get().getElement(), Event.ONKEYDOWN);
    }

....

private static boolean checkBrowser(String browserName) {
    return (Window.Navigator.getUserAgent().toLowerCase().indexOf(browserName.toLowerCase()) != -1);
}

-- EDIT --

Here is the code detect browser Back button also. For more info have a look at

How to know whether refresh button or browser back button is clicked in firefox

public native void onBeforeUnload()/*-{

    $wnd.onbeforeunload = function(e) {
        return 'Are you sure?';
    };
}-*/;

public void onModuleLoad() {

    onBeforeUnload();

}

screenshots (browser back button is clicked or page is refreshed)

Please have a look at below posts:

• GWT back button browser
• Best way to detect browser closing/navigation to other page and do logout