Hi Jason,
Use below code.It's working fine
createContent : function(oController) {
var myButton = new sap.ui.commons.Button("btn");
myButton.setText("Hello World");
myButton.attachPress(function(){$("#btn").fadeOut();});
return myButton;
}
For UI5 applications you have to disable web security,If you didn't apply use below link
http://stackoverflow.com/questions/3102819/chrome-disable-same-origin-policy
Regards
Shruti