How to load a Javascript in WebView

Question

I have loaded my Webpage in Android WebView using webview.loadUrl() and I am trying to inject a Javascript into the WebView using webview.evaluateJavascript().

But the problem here is, the Javascript is available in a remote location/url. I want to get the javascript from a remote location and inject it into WebView.

I have searched related to this question but all I have found is loading from string.

You will need to download it yourself with an http library like okhttp — Ahmad
– Ahmad, Commented Sep 10, 2019 at 1:39

源贵董 · Accepted Answer · 2019-09-10 10:57:48Z

You can do it like this :

private static class WC extends WebViewClient {
    Handler handler1 = null;
    WebView webView = null;
    byte[] b = null;

    public WC(Handler handler, WebView webView) {
        this.handler1 = handler;
        this.webView = webView;
    }

    @Override
    public void onPageFinished(final WebView view, String url) {
        super.onPageFinished(view, url);
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    injectScriptFromNetWork("http://192.168.216.254:4000/test.js");
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();

    }

    private void injectScriptFromNetWork(String urlStr) throws IOException {

        URL url = new URL(urlStr);
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        int code = urlConnection.getResponseCode();
        if (code == 200) {
            InputStream inputStream = urlConnection.getInputStream();
            b = new byte[inputStream.available()];
            inputStream.read(b);
        }

        handler1.post(new Runnable() {
            @Override
            public void run() {
                String jsSource = Base64.encodeToString(b, Base64.NO_WRAP);
                webView.loadUrl("javascript:(function() {" +
                        "var parent = document.getElementsByTagName('head').item(0);" +
                        "var script = document.createElement('script');" +
                        "script.type = 'text/javascript';" +
                        "script.innerHTML = window.atob('" + jsSource + "');" +
                        "parent.appendChild(script)" +
                        "})()");
            }
        });
    }
}

MainActivity.java code like this:

handler = new Handler(getMainLooper());
webView.setWebViewClient(new WC(handler, webView));
webView.loadUrl("file:///android_asset/index.html");

Forgave me, this is my first time answering questions on stackoverflow.

SO users always try to improve things, no apologies required. You can visit StackOverflow code of conduct to know how to write good question/answer. Your answer is primarily code-based. try to explain it rather giving a code snippet only. It will help the community for future reference.

Jakir Hossain · Accepted Answer · 2019-09-10 03:25:23Z

1

To enable javascript try this.

WebView myWebView = (WebView) findViewById(R.id.webview);

myWebView.getSettings().setJavaScriptEnabled(true);

myWebView .loadUrl("url");

To get the javascript from a remote location see This solution

edited Sep 10, 2019 at 3:25

answered Sep 10, 2019 at 3:19

Jakir Hossain

3,9401 gold badge17 silver badges29 bronze badges

Collectives™ on Stack Overflow

How to load a Javascript in WebView

2 Answers 2

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related