main.js

...

handleConnectionChange = (event) => {
  if(event.type == "online"){
   // Setup the request
   var headers = new Headers();
  // Set some Headers
  headers.set('Accept', 'application/json');

  // Get Data from indexedDB
  var name = return idb.open('personal_details', 1).then(function(db) {
    var tx = db.transaction(['form_data'], 'readonly');
    var store = tx.objectStore('form_data');
    return store.getAll();
  })

  // Post data to server
  name
  .then(function(data) {
    formData.append('name', data['name']);

    var response = fetch(<server post endpoint>, {
      method: 'POST',
      headers,
      body: formData
    });

    // If Post succeeds, delete data from IndexedDB
    response
    .then(function(){
        // Delete locally stored data after successful post to server
        idb.open('restaurant', 1).then(function(db) {
          const tx = db.transaction('form_data', 'readwrite');
          const store = tx.objectStore('form_data');
          store.clear();
        })
      })

  })
}
}