Chrome Storage OnChanged - Javascript

Chrome storage onChanged is a feature in Javascript that listens for changes in Chrome's local or sync storage. When the storage changes, the onChanged event fires and allows you to execute a callback function to handle the changes.

Importing the onChanged Event

To use the onChanged event in your Javascript code, you need to first import it from the Chrome extension namespace:

chrome.storage.onChanged.addListener(function(changes, namespace) {
  console.log('Storage changed');
});

Registering the onChanged Callback

Next, you will need to register your onChanged callback function with the onChanged event. The onChanged function takes two arguments: the changes object and the namespace. The changes object contains the new values of the storage keys that changed, while the namespace specifies whether the storage is local or sync.

chrome.storage.onChanged.addListener(function(changes, namespace) {
  for (var key in changes) {
    var storageChange = changes[key];
    console.log('Storage key "%s" in namespace "%s" changed. ' +
                'Old value was "%s", new value is "%s".',
                key,
                namespace,
                storageChange.oldValue,
                storageChange.newValue);
  }
});

Using the onChanged Event

Once the onChanged callback is registered, you can use it to listen for changes in Chrome's storage. For example, if you have a key called "username" in your local storage, you can use the onChanged event to track any changes made to it like so:

chrome.storage.onChanged.addListener(function(changes, namespace) {
  if (changes.hasOwnProperty('username')) {
    var storageChange = changes['username'];
    console.log('Username changed from "%s" to "%s" in namespace "%s".',
                storageChange.oldValue,
                storageChange.newValue,
                namespace);
  }
});

Conclusion

In conclusion, the Chrome storage onChanged event is a powerful tool that enables you to listen for changes in Chrome's local or sync storage. By registering an onChanged callback function with the onChanged event, you can keep track of any changes made to the storage keys you're monitoring.