Javascript – How do I check if the WebView Javascript interface is available?

If a JavaScript interface is available/defined, is there any correct way to check JavaScript in WebView?

The idea is to define a check method in the interface that can be called and simply return a true if available. Isn’t there a suitable “official” way to do this? Because if the interface is not available/undefined, it throws an error.

I’m using Android, that’s why Java code :

webView.addJavascriptInterface(new WebAppinterface(this),"InterfaceName");

@JavascriptInterface
public void isInterfaceAvailabe (){
   return true;
}

In Javascript:

function hasJavaScriptInterface () {
   if (InterfaceName.isInterfaceAvailable()){
      return true;
   }
   else {
      return false;
   }
}

Thanks for the answer!

First you need to check if the InterfaceName is actually exported, that is, whether it appears as a property of the window object. You can do this in a number of ways:

if ("InterfaceName" in window) ...

or

if (window. InterfaceName) ...

or

if (typeof window. InterfaceName === "function") ...

Because if you just try to call an undefined property, you get an error: Uncaught TypeError: window. InterfaceName is not a function