I have a web page that loads a Javascript .js library. It works correctly with browsers on Windows (Firefox) or Android (Chrome). It's not loading in a WebView. I've added Javascript alert statements in the Javascript in the HTML and in the .js libraries as a test. I can see it's working on...
www.b4x.com
And it turns out javascript is enabled by default in webview, so you probably just need to add the chromeclient as shown above.