How can I see Javascript errors in WebView in an Android app?

You can actually receive the console messages from a WebView, which would allow you to catch the errors that it throws.

To do so:

1. Enable JavaScript on your WebView
2. Set a WebChromeClient
3. Override onConsoleMessage

Example:

    final WebView webView = (WebView) findViewById(R.id.webview_terms_conditions);

    WebSettings webSettings = webView.getSettings();
    webSettings.setJavaScriptEnabled(true);

    webView.setWebChromeClient(new WebChromeClient() {
        @Override
        public boolean onConsoleMessage(ConsoleMessage consoleMessage) {
            Log.d("MyApplication", consoleMessage.message() + " -- From line "
                    + consoleMessage.lineNumber() + " of "
                    + consoleMessage.sourceId());
            return super.onConsoleMessage(consoleMessage);
        }
    });

    webView.loadUrl(getString(R.string.url_terms_conditions));

Similar to what it says here, though that doc isn’t complete and it uses a deprecated method.

When running on Android KitKat, you can also enable remote debugging!