Implement 'change' event

[manolo]

Like in vaadin-combo-box we should consider this event, see vaadin/vaadin-combo-box#271

[robrez]

It seems that the current value-changed event fires when the vaadin-date-picker value is changed imperitively (not triggered by user input)... I wonder if it would be agreeable to fix that, as well, when the change event is implemented.

[robrez]

Still would like to see this implemented; Currently, vaadin-date-picker uses vaadin-text-field -- which does publish change events;

However events don't propagate accross shadow dom boundaries. This snippet seems to indicate that vaadin-date-picker would have to play that same game that vaadin-text-field does:

    _onChange(e) {
      // In the Shadow DOM, the `change` event is not leaked into the
      // ancestor tree, so we must do this manually.
      const changeEvent = new CustomEvent('change', {
        detail: {
          sourceEvent: e
        },
        bubbles: e.bubbles,
        cancelable: e.cancelable,
      });
      this.dispatchEvent(changeEvent);
    }

https://github.com/vaadin/vaadin-text-field/blob/master/src/vaadin-text-field-mixin.html#L250-L257

Alternatively, date-picker-light can be used and change events can be added to the light-dom input. I'm not really so sure that the events published by the overlay element would be available or sufficient to indicate a user-initiated change occurred. Maybe value diffing on-blur would work there

[ndormont]

Probably a noob question: Why not just use on-value-changed ?