Attaching a click handler in a cross-browser way
The common thing in your code is the listener.

function massClickListener() {
    doMassClick( btnArray[index], nameArray[index]);
}


Then it is easier to use the ternary:

btnArray[index][ window.addEventListener ? 'addEventListener' : 'attachEvent'](window.addEventListener ? 'click' : 'onclick', massClickListener);


Personally however, I think this is better:

if (window.addEventListener) {
    btnArray[index].addEventListener('click', massClickListener);
} else {
    btnArray[index].attachEvent('onclick', massClickListener);
}


Using the conditional operator to choose different methods is not very readable.

Another option might be to use a framework that does these kinds of things for you.