Block/Disable tabs in TabNavigator - react-navigation

Question

I have a TabNavigator as shown in the picture. Header Image

I am using TabNavigator for creating these tabs as below.

const Tab_Navigator = TabNavigator({
    First:{
        screen: First,
    },
    Second:{
        screen: Second,
    },
    Third:{
        screen: Third,
    },

Now I want to block/disable "Second" and "Third" tabs. It should be visible but one shouldn't able to navigate to them.

I tried blocking these tabs as shown here but I guess I am missing something. My try:

Tab_Navigator.router.getStateForAction = (action, state) => {
if( action.type === NavigationActions.navigate({ routeName: "Second"}) ||
    action.type === NavigationActions.navigate({ routeName: "Third"}))
{
    return null;
}

return Byte.router.getStateForAction(action, state);

};

Answer 1

In this case, the action.type = "Navigation/NAVIGATE" and action.routeName is the name of your tab. It is just a little different from the ReactNavigation Routers example. The following should work:

const defaultGetStateForAction = Tab_Navigator.router.getStateForAction;

Tab_Navigator.router.getStateForAction = (action, state) => {
  if ((action.type === NavigationActions.NAVIGATE) &&
     (action.routeName === "Second" || action.routeName === "Third") {
    return null;
  }

  return defaultGetStateForAction(action, state);
};

EDIT: Here is an image of the the Chrome Debugger stopped at a breakpoint in a very similar piece of code(tab names are different), but it shows the values of the "action" object being passed into this function.