Exchange Data

The exchange data module system.exchange is used to store cross-app shared data, which is persistently stored in the system's shared storage. Data stored in system.exchange can be accessed by all apps, so this module can be used to store some configuration information for apps, but it is not suitable for storing sensitive data.

system.exchange stores data in the form of key-value pairs, where the key must be a string and the value is a JSON value (or a JavaScript value that can be serialized to JSON).

Importing Modules

import exchange from '@system.exchange'

API

method

Gets the value corresponding to the key name key in storage. Returns undefined if the key-value pair does not exist.

method

This method accepts a key name key and a value value as parameters and adds this key-value pair to storage. If the key name already exists, its corresponding value is updated.

method

Deletes the key-value pair corresponding to the key name key in storage. Returns true if the key-value pair exists and is successfully deleted.

method

Watches for changes in the data value with the key name key in storage, and calls the callback function when the value changes. The parameter value of the callback function is the new data value. The watch() method returns a watcher ID, which can be used in the unwatch() method to stop watching.

Tips

When watching is no longer needed, the unwatch() method should be used to stop watching, otherwise it may cause memory leaks.

method

Cancel a watch for the key name key in storage. The parameter watcherID is the watcher ID returned when the watch was created by the watch() method.