Overview of multiple async request

multiple_requests_overview.js

/**
 * Aggregates results from the API calls
 */
function aggregateResults(results) {}

app.get('/endpoint', function(req, res) {
  var apiUrls = [
    'http://api/endpoint1',
    'http://api/endpoint2',
    'http://api/endpoint3',
  ];
  
  var results = [];
  
  // make requests to all apiUrls and save result of each call in `results`
  //  ??????????????????
 
  // do something with all the results
  var aggregatedResults = aggregateResults(results);
  
  // send processed results to client
  res.send(aggregatedResults);
});