Webview: block JavaScript popups

Question

Right now I'm using this line of code to at least try to block popups by JavaScript in webview:

webview.getSettings().setJavaScriptCanOpenWindowsAutomatically(true);

1) I don't get it why I have to switch this to "true" that it's working
2) are there any other techniques for blocking popups in webview?

Help is much appreciated.

Answer 1

preamble

We are at the WebView setup side of the equation.
At first glance an obvious comment, but if you don't need JavaScript, don't enable JavaScript, then you don't get JavaScript popup's. I'm assuming you DO need JavaScript (remember it may be XSS vulnerable) and want to do what you can to disable the popups that can inevitably follow.

INFO:

WebViewClient. Override this behavior of your WebView, e.g. so links open within your WebView. WebChromeClient lets you handle Javascript's alert() and other functions.
OP(1)setJavaScriptCanOpenWindowsAutomatically(true) is usually blocked only when done outside of an event handler.
OP = Original Post ;O).

Let's setup a senario

This is how I setup my normal webview:

WebView webView = (WebView) this.findViewById(R.id.webView1);//CustomWebView ?

WebSettings webView_settings = webView.getSettings();

//by setting a WebClient to catch javascript's console messages :

WebChromeClient webChromeClient = new WebChromeClient() {
        public boolean onConsoleMessage(ConsoleMessage cm) {
            Log.d(TAG, cm.message() + " -- From line "
                    + cm.lineNumber() + " of "
                    + cm.sourceId() );
            return true;
        }
    });
webView_settings.setDomStorageEnabled(true);

WebViewClient webViewClient = new WebViewClient() {
        @Override
        public void onPageFinished(WebView view, String url) {
            super.onPageFinished(view, url);
            setTitle(view.getTitle());
            //do your stuff ...
            }
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if (url.startsWith("file")) 
        {
            // Keep local assets in this WebView.
             return false;
        }
      }
    });

//webView.setWebViewClient(new HelpClient(this));//
webView.setWebChromeClient(webChromeClient);
webView.setWebViewClient(webViewClient);
webView.clearCache(true);
webView.clearHistory();
webView_settings.setJavaScriptEnabled(true);//XSS vulnerable set to false ?
webView_settings.setJavaScriptCanOpenWindowsAutomatically(true);//set to false ?
webView.loadUrl("file:///android_asset/connect.php.html");//load something

OP(2) Let's block what we can

From @markproxy If you extend WebChromeClient, you can override its onJsAlert() method and block the built-in handler for alerts. While you're at it, you will probably want to block calls to the confirm() and prompt():

WebChromeClient webChromeClient = new WebChromeClient() {
    @Override
    public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
        result.cancel();
        return true;
    }

    @Override
    public boolean onJsConfirm(WebView view, String url, String message, JsResult result) {
        result.cancel();
        return true;
    }

    @Override
    public boolean onJsPrompt(WebView view, String url, String message, String defaultValue, JsPromptResult result) {
        result.cancel();
        return true;
    }
};

webView.setWebChromeClient(webChromeClient);

Answer 2

You can try block popups (windows) in WebChromeClient:

@Override
public boolean onCreateWindow(WebView view, boolean isDialog, boolean isUserGesture, Message resultMsg) {
    WebView newWebView = (WebView) LayoutInflater.from(view.getContext()).inflate(R.layout.webview_custom_view, null);
    WebView.WebViewTransport transport = (WebView.WebViewTransport) resultMsg.obj;
    transport.setWebView(newWebView);
    resultMsg.sendToTarget();
    return true;
}

Object newWebView should add to some container like a view.It's example of creating the window (popup) from WebView.

Answer 3

I had to do this. Override the onJSAlert() method in the WebChromeClient class:

MyWebChromeClient myWebChromeClient = new MyWebChromeClient();
webView.setWebChromeClient(myWebChromeClient);

MyWebChromeClient is a custom Class that Inherits WebChromeClient

public class MyWebChromeClient extends WebChromeClient {

    @Override
    public boolean onJsAlert(WebView view, String url, String message, JsResult result)
    {
        final JsResult finalRes = result;
        new AlertDialog.Builder(view.getContext())
            .setMessage(message)
            .setPositiveButton(android.R.string.ok,
                    new AlertDialog.OnClickListener()
                    {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            finalRes.confirm();  
                        }
                    })
            .setCancelable(false)
            .create()
            .show();
        return true;
    }
}