JavaScript alert dialogs in WebView - How to make them work

By default, WebView does not implement JavaScript alert dialogs, ie. alert() will do nothing. In order to make you need to firstly enable JavaScript (obviously..), and then set a WebChromeClient to handle requests for alert dialogs from the page:

webView.setWebChromeClient(new WebChromeClient() {
    //Other methods for your WebChromeClient here, if needed..

    @Override
    public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
        return super.onJsAlert(view, url, message, result);
    }
});

Here, we override onJsAlert, and then we call through to the super implementation, which gives us a standard Android dialog. You can also use the message and URL yourself, for example if you want to create a custom styled dialog or if you want to log them.