I am new to this. Based on our project req. I have to create unique aura:id to support dynamic appending of elements. I researched on this aura:id does not support expression. Two question

1. Can I use global id like `<a id = "{! GlobalId + '_tab' + index}">` where anchor tag will be in an iteration; so that i have a unique id for each anchor tag.

2. How can i get this unique id; the way i am using right now is 

    

> var globalId = component.getGlobalId(); globalId = globalId + "_tab0";
>
> var activeTab = component.find(globalId);
>
> $A.util.addClass(activeTab,'slds-active');

 I am getting the global id but how to find an element with global id?

Is this approach right?