SO 47463850

addEventListener and window.open

HTML

<div>
  <button id="file1" data-url="https://www.google.com">file 1</button>
  <button id="file2" data-url="https://www.slashdot.org">file 2</button>
</div>

JavaScript

var buttons = document.querySelectorAll('button');
for(var i = 0; i < buttons.length; i++) {
    buttons[i].addEventListener('click', openNewTab, false);
}

function openNewTab(event) {
   window.open(event.target.dataset.url, '_blank');
}