iOS-JavaScript sharing data no. 2

iOS-javascript-sharing-data-no-2.js

function fetchDataFromDatabase(query) {
  
  // Calling iOS method here
  
  return new Promise((resolve, reject) => {
    
    // Timeout and reject.
    let timeoutId = setTimeout(() => reject(new Error('Timeout')), 3000);

    Rx
      .Observable
      .create(function subscribe(observer) {
        // This will be called by the iOS client
        didReceiveDataFromDatabase = function(data) {
          // Parse, process your data if needed.
          observer.next(JSON.parse(data));
        }
      })
      .subscribe(result => {
        // Receiving data here, resolving promise
        resolve(result);
      });
  });  
}