How do I access the trello API from Powerup?

How can I make requests against the trello API due to powerup? This seems like such an obvious question, but it doesn't seem to be covered, which I can find.

My simple powerup looks like this:

var boardButtonCallback = function(t){
  return t.popup({
    title: 'Tools',
    items: [
      {
        text: 'Hide Duplicates',
        callback: function(t){

          var cardQueryCb = function(result){
            console.log(result);
          }
          var cardQ = 'https://trello.com/1/boards/[board_id]/cards/all';
          fetch(cardQ).then(function(response) {
            return response.json();
          }).then(function(data) {
            console.log(data);
          });

          return t.cards('id', 'name')
          .then(cardQueryCb);
        }
      }
    ]
  });
};

TrelloPowerUp.initialize({
  'board-buttons': function(t, options){
    return [{
      text: 'Duplicates',
      callback: boardButtonCallback
    }];
  }
});

      

        
        
        
      

    

The response object after a call to retrieve says that the call is unauthorized.

I would have thought that calling this code from the power-on context would be considered authorized. While I am logged into trello, I can post this address in my browser and get the correct answer - why does the javascript call also not result in a valid response?

More importantly, how can I get a successful response from this URL?