state

Property

Property is a class that monitors a value and notifies listeners whenever it has changed.

// creates the property, defaulting the value to false
const isPaused = new Property(false);

// subscribe for changes to the property
isPaused.subscribe(function(newValue, oldValue) {
  console.log('Value changed from', oldValue, 'to', newValue);
});

// the property can change similarly to the previous case, the handler triggering appropriately
isPaused.value = true;

A Property only notifies listeners when the value set is different than the current value it has. To tell the Property to always notify regardless if the values are equal, provide a true as a second argument in the constructor.

const width = 1024;
const height = 768;

// Creates a property that will always notify.
const aspectRatio = new Property(width / height, true);

// subscribe for changes to the property
aspectRatio.subscribe(function(newValue, oldValue) {
  if (newValue === oldValue) {
    console.log("Property value has not changed, but the listener was still called.");
  }
});

aspectRatio.value = width / height;

UserData

The UserData provides a mechanism for storing game/session data outside of the game instance by saving it in localStorage at the Container level. This mechanism can be used to share information across games on the same domain. Since this feature relies on Bellhop communication, you must wait for Bellhop to be connected first

import { UserData } from 'springroll'

app.container.on('connected', async () => {
    await UserData.write('my-value', { foo:'bar' });

    const value = await UserData.read('my-value');
    console.log('Value retrieved:', value);

    await UserData.delete('my-value');
});