Android WebView always returns null for javascript getElementById on loadUrl

Question

I try to fill out a form inside a webview from the android client app. I know how it should work, but the getElementById always returns null for me. I tried it on different websites.

Here is my example for www.google.com.

MyWebView view = new MyWebView(this);
view.getSettings().setJavaScriptEnabled(true);
view.loadUrl("http://www.google.com");
view.setWebViewClient(new WebViewClient() {
    @Override
    public boolean shouldOverrideUrlLoading(WebView v, String url) {
        v.loadUrl(url);
        return true;
    }
    @Override
    public void onPageFinished(WebView v, String url) {
        v.loadUrl("javascript:document.getElementById('mib').value = 'aaa';");              
    }
});
setContentView(view);

And the MyWebView class (only for information).

class MyWebView extends WebView {
    Context context;
    public MyWebView(Context context) {
        super(context);
        this.context = context;
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // do some multi touch stuff
        return true;
    }
}

I always get the error:

09-01 04:35:26.453: I/chromium(2962): [INFO:CONSOLE(1)] "Uncaught TypeError: Cannot set property 'value' of null", source: https://www.google.de/?gws_rd=ssl (1)

But the element "mib" should be on the site. Using a desktop browser (chrome with mobile simulation) everything is working fine. I have no idea, whats going wrong here.

Thanks for hints!

Edit: I got some progress. Regarding this site, I also need setDomStorageEnabled(true). No I can find the DOM object and set the value, but instead of showing the modified site I get a new blank one with only the value I set. E.g. a white blank site with the text "aaa".

i think u want to use webview with WebViewClient

Naveen Tamrakar
– Naveen Tamrakar

2014-09-01 09:09:14 +00:00
Commented Sep 1, 2014 at 9:09 — Naveen Tamrakar
– Naveen Tamrakar, Commented Sep 1, 2014 at 9:09
But view is from the type WebView.

Catscratch
– Catscratch

2014-09-01 09:55:33 +00:00
Commented Sep 1, 2014 at 9:55 — Catscratch
– Catscratch, Commented Sep 1, 2014 at 9:55

akrolsmir · Accepted Answer · 2015-07-30 22:58:39Z

35

Finally I found a solution! And it is a really strange behaviour.

First of all you need to specify setDomStorageEnabled(true) on your webview. Otherwise the DOM doesn't work. I wonder why no tutorial gave a hint about. But ok.

myview.getSettings().setDomStorageEnabled(true);

After this I ended up in a white blank page with only the value I set. The strange thing is, that javascript:document.getElementById('myfield').value = 'aaa'; returns a value. Namely the one I set. So a new blank page was created that only contains the string "aaa".

I solved it by modifying the javascript to throw away the return result:

javascript:var x = document.getElementById('myfield').value = 'aaa';

And voilá. It is working.

edited Jul 30, 2015 at 22:58

akrolsmir

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answered Sep 1, 2014 at 12:39

Catscratch

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5 Comments

Huy Tower Over a year ago

Actually, Your issue not happened before Android 4.4, Since Google already changed to new WebView is more better from Android 4.4 version.

Huy Tower Over a year ago

I don't know why, but actually codes need put declare thing as "var x". Now It's work.

Shishir Shetty Over a year ago

Like a BOSS !! @Catscratch. Like a BOSS !!

Sagar Nayak Over a year ago

any full example , please .

Sagar Nayak Over a year ago

@catscratch please look at this stackoverflow.com/questions/37644551/… . it needs help.

Stefan Anca · Accepted Answer · 2015-11-16 19:49:05Z

15

I also struggled with this issue for quite some time. I had the same issue with the blank page as @Catscratch and nothing worked. Strangely enough, if you wrap the same code in a Javascript function, it all works.

Thus,

 webView.loadUrl("javascript:(function() { document.getElementById('email_field').value = '" + email + "'; })()");

works, while

webView.loadUrl("javascript:document.getElementById('email_field').value = '" + email + "';");

does not work.

And all of this without needing setDomStorageEnabled(true) and without setWebChromeClient()

answered Nov 16, 2015 at 19:49

Stefan Anca

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2 Comments

Neal Over a year ago

Can you suggest me where i have to pass main URL or pass main URL and than i loadUrl of javascript

TheRealChx101 Over a year ago

None of these work. document.getElementsByTagName('a'); returns undefined inside WebView but works when accessed on desktop

rogerdpack · Accepted Answer · 2017-10-10 04:57:58Z

0

Another work around that seems to work: make sure you javascript "returns" null, ex:

loadUrl("javascript:document.getElementById('myfield').value = 'aaa'; null");

Oddly however, if you aren't using getElementById then it's OK for loadUrl to return values, the same behavior doesn't occur. Smells like some kind of bug...it might be this bug but possibly not fixed in some versions of android [?]

edited Oct 10, 2017 at 4:57

answered Oct 10, 2017 at 4:37

rogerdpack

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