Previously, event listeners for component output events attached on an
Angular custom element before inserting it into the DOM (i.e. before
instantiating the underlying component) didn't fire for events emitted
during initialization lifecycle hooks, such as `ngAfterContentInit`,
`ngAfterViewInit`, `ngOnChanges` (initial call) and `ngOnInit`.
The reason was that `NgElementImpl` [subscribed to events][1] _after_
calling [ngElementStrategy#connect()][2], which is where the
[initial change detection][3] takes place (running the initialization
lifecycle hooks).
This commit fixes this by:
1. Ensuring `ComponentNgElementStrategy#events` is defined and available
for subscribing to, even before instantiating the component.
2. Changing `NgElementImpl` to subscribe to `NgElementStrategy#events`
(if available) before calling `NgElementStrategy#connect()` (which
initializes the component instance) if available.
3. Falling back to the old behavior (subscribing to `events` after
calling `connect()` for strategies that do not initialize `events`
before their `connect()` is run).
NOTE:
By falling back to the old behavior when `NgElementStrategy#events` is
not initialized before calling `NgElementStrategy#connect()`, we avoid
breaking existing custom `NgElementStrategy` implementations (with
@remackgeek's [ElementZoneStrategy][4] being a commonly used example).
Jira issue: [FW-2010](https://angular-team.atlassian.net/browse/FW-2010)
[1]: c0143cb2ab/packages/elements/src/create-custom-element.ts (L167-L170)
[2]: c0143cb2ab/packages/elements/src/create-custom-element.ts (L164)
[3]: c0143cb2ab/packages/elements/src/component-factory-strategy.ts (L158)
[4]: f1b6699495/projects/elements-zone-strategy/src/lib/element-zone-strategy.tsFixes#36141
PR Close#37570
eba9dd364e