lastMessageType property represents the type of the last message in the thread.
var type = instanceOfMozMobileMessageThread.lastMessageType;
A string. Possible values are
This is a non-standard implementation, but it is discussed at W3C as part of the System Application Working Group.
|Messaging API||Editor's Draft||Editor Draft (WIP).|
For obvious reasons, support is primarily expected on mobile browsers.
Supported in Firefox OS 1.0.1.