Using attribute that can uniquely identify an element on the page

Development Quality Assurance
1

Most of the elements on a page share similar attributes But I want to trigger an element on the page with a unique attribute. Any clue on this!

2

is this something on github ,can you share the github link

3

No!
In an implementation am invoking an element on a web page by its className But realised there exists other elements with similar className on the same page. So I want to trigger this element with a unique attribute

4

could you explain more on this on what you are trying to accomplish