The Changed.[propertyName] event, that fires when a state property of a UIZE class instance changes value, has been improved with the addition of a newValue property in the event object.

Now, when a Changed.[propertyName] event fires for a particular state property that has changed value, the event object that is passed as an argument to any handlers of the event will contain a newValue property to indicate the new value of the state property.

This allows us to access the new value of the state property without having to access the instance that owns the property in order to call its get method to get the value for the property.

INSTEAD OF...

myWidget.addChild ('slider',Uize.Widget.Bar.Slider).wire (
  'Changed.value',
  function (event) {
    console.log (event.source.get ('value'));
  }
);

USE...

myWidget.addChild ('slider',Uize.Widget.Bar.Slider).wire (
  'Changed.value',
  function (event) {
    console.log (event.newValue);
  }
);

In the above example, we're adding a slider child widget to the myWidget parent widget. Because the addChild instance method returns a reference to the added child widget, we can chain a call to the child's wire method in order to wire a handler for its Changed.value event.

Now, without the newValue property of the event object, we could either access the new value by getting to the instance through the source object of the event (as in event.source.get ('value')), or we could dereference the child widget from the myWidget parent (as in myWidget.children.slider.get ('value')).

Both of these approaches are more cumbersome than simply using the newValue property that is provided as part of the event object for Changed.[propertyName] events.