A.use vs A.ready

aui-use-vs-ready.md

AUI().use('aui-button', function(A) {
   // This code will fire when
   // aui-button module and its
   // dependencies are loaded
});

Now, there are times when you want to both load some modules and fire your callback on DOM ready, so here is how you would do that in Alloy:

AUI().ready('aui-button', function(A){ 
   // This code will fire on DOM ready 
   // and when this module and its
   // dependencies are ready
});