Check existence of attributes with Dalek

gistfile1.js

test.execute(function () { 
  var nl = document.querySelectorAll(".menubar a[href]"); 
  var as = Array.prototype.slice.call(nl); 
  as.foreach(function (el) {
    var attr = el.getAttribute('data-tracking-id');
    this.assert.ok((attr !== null), 'Attribute exists for:' + el.outerHTML);
  }.bind(this)) 
})