Does a Facebook canvas app need a login button? -

I want to get an access token to access the graph API from my canvas app using Javascript SDK. Here's my code:

  FB.init ({appId: conf.FACEBOOK_APP_ID, xfbml: true, channelUrl: window.location.protocol + '//' + window.location.host + ' /channel.html '}); FB.getLoginStatus (function) {var accesstooken = response.authResponse.accessToken; [...]}   
 However, it assumes that the user is logged in by visiting the app. Javascript SDK documentation test before receiving the entry token  
  if (response.status === 'connect')   
 It is not clear that it means Only for external sites that ask users to enter Facebook, or it is also applicable to the canvas app. My impression is that the canvas app can be accessed only within Facebook, and therefore the user needs to be logged in to access them. I have two related questions:  
  1. What reaction is needed? Thats is necessary?  Can a user ever access the canvas app without logging in?  
  2. What Facebook Canvas app needs a login button?    
 
 
 
 
 what feedback is required. what is required? Can a user ever use a CA without the Navas app without logging in?    
 Of course they can.  
 
 
 Do a Facebook Canvas app require a login button?            
 to use Give advice.