CF-Incidents Workers - Event and EventTarget spec compliance improvements

[ENF News Bot]

Several improvements bring the Workers runtime's Event, EventTarget, and related APIs closer to their web platform specifications.

isTrusted is now correct for user-constructed events​

https://developers.cloudflare.com/c...ed-is-now-correct-for-user-constructed-events

User-constructed event subclasses (new MessageEvent(...), new CustomEvent(...), new ErrorEvent(...), new CloseEvent(...)) now correctly report isTrusted as false. Previously, these incorrectly reported isTrusted as true.

on<type> handlers fire in registration order​

https://developers.cloudflare.com/changelog/rss/#ontype-handlers-fire-in-registration-order

Event handler attributes such as onmessage and onabort now fire in their registration order relative to addEventListener() calls, matching browser behavior. Previously, on<type> handlers always fired before any addEventListener() listeners regardless of when they were assigned.

MessageEvent constructor improvements​

https://developers.cloudflare.com/changelog/rss/#messageevent-constructor-improvements

new MessageEvent(type) now works without providing an init object — data defaults to null per spec. The MessageEventInit dictionary also now supports the full spec surface: origin, lastEventId, source, and ports, in addition to data.

CloseEvent and ErrorEvent constructor improvements​

https://developers.cloudflare.com/changelog/rss/#closeevent-and-errorevent-constructor-improvements

The CloseEventInit and ErrorEventInit dictionaries now accept the standard EventInit members bubbles, cancelable, and composed.

MessagePort starts on any message listener​

https://developers.cloudflare.com/changelog/rss/#messageport-starts-on-any-message-listener

Adding a message event listener to a MessagePort via addEventListener("message", ...) now starts the port, matching browser behavior. Previously, only assigning onmessage would start the port.

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