gistfile1.txt

var url = '/scripts/main.min.c18e3e78.js';

var opaqueResponsePromise = function(response) {
  console.log('opaque repsonse', response);
  
  // Cache opaque response
};

var basicResponsePromise = function(response) {
  console.log('basic repsonse');
  // Parse the response
  
  if(response.status !== 200) {
    throw new Error('Bad status code');
  }
  
  return response.text()
      .then(function(text) {
        console.log('Response.text is complete');
      })
      .catch(function(err) {
        console.log('Oops = ', err);
      });
};

fetch(url, {'mode': 'cors'})
  .then(function(response) {
    if (response.type === 'opaque') {
      console.log('The Response is opaque so we can\'t examine it');

      // Do something with the response (i.e. cache it for offline support)
      return opaqueResponsePromise(response);
    }
    
    return basicResponsePromise(response);
    
  })
  .catch(function(err) {
    console.error('Fetch Error :-S', err);
  });