How to access elements using Javascript with no id : I'm trying to access an element that has no id and has a shared classname, using Javascript.How can I successfully do that?

I tried using document.getElementsbyClassName property but since the classname is shared by other elements, this is not working. 

    <a class="sharedClass anotherClass" href="www.mybooks.com" data-m="{"CN":"uniquename"}"> Proceed </a>

//I want to be able to click Proceed element from the above code. Please note that uniquename is unique to this element. I'm thinking we can use that somehow here but am not really sure.