Gaia/System/NewModule

If you want to add a new functionality, a.k.a., a new script or a new module into system app after bug 1094759, please read this.

If you want to use BaseModule

Great! It's providing a promise based start procedure and what you need to do.

 var NewModule = function() {};
 BaseModule.create(NewModule, {
   name: 'NewModule',
   _start: function() {
     // return a promise if your start progress involves some asynchronous operation
     // return null or do not return, then we will unblock your module from the starting process right away once
     // yourModule.start() is called
     // BaseModule has a native start() function to process not only your own starting (this._start()) but also the child
     // module's start() function. The whole starting process will be resolved only when all the children's start process
     // is resolved.
   }
 });

If you don't want to use BaseModule

It's okay. But you have to provide this interface for us:

 var NewModule = {
   start: function() {
     // return a promise if your start progress involves some asynchronous operation
     // return null or do not return, then we will unblock your module from the starting process right away once
     // yourModule.start() is called
   }
 };

No matter what you choose to go

Don't put your new script in the header of system app. If it's necessary to go alive when booting, please find a proper parent module and lazy load it. If you are using BaseModule, 1. Put the module in the parent module's SUB_MODULES if you think it's blocking the starting progress of the parent module. 2. If the new module is not as important to block the parent, use this.loadWhenIdle([NEW_MODULE]) in parent's start function 3. If the new module is only serving some on demand request, consider to lazy load the new module in the parent module's event handler and start it.