java - How to call javascript from Android?

Question

How do we call javascript from Android? I have this javascript library which I would like to use, I want to call the javascript function and pass the result value to the android java code. Haven't found the answer from now. i managed to call android code from javascript, but I want the other way around.

Answer 1

There is a hack:

1. Bind some Java object so that it can be called from Javascript with WebView:

   addJavascriptInterface(javaObjectCallback, "JavaCallback")
   

2. Force execute javascript within an existing page by

   WebView.loadUrl("javascript: var result = window.YourJSLibrary.callSomeFunction();
       window.JavaCallback.returnResult(result)");
   

(in this case your java class JavaObjectCallback should have a method returnResult(..))

Note: this is a security risk - any JS code in this web page could access/call your binded Java object. Best to pass some one-time cookies to loadUrl() and pass them back your Java object to check that it's your code making the call.