MessageEventInit
inline fun MessageEventInit(
data: Any? = null,
origin: String? = "",
lastEventId: String? = "",
source: UnionMessagePortOrWindow? = null,
ports: Array<MessagePort>? = arrayOf(),
bubbles: Boolean? = false,
cancelable: Boolean? = false,
composed: Boolean? = false
): MessageEventInit (source)Platform and version requirements: JS