Return value missed in close after viewing

Question

My original script looks like this:

(function() {
    // result = doSomeWorks()
    return result;
})();

Why can I get the return value from the API, for example, chrome.tabs.executeScriptor execute_scriptselenium / webdriver.

But after the script is renamed ( http://pastebin.com/7dBJuGzL ), the return value is simply skipped. I always get the value nullfrom the above APIs.

Is there any solution / workaround for this? Or perhaps trying to get the return value from a browser script, is that just not idiomatic for Browserify?

Thanks in advance.