Collect font information from all ElementNodes

gistfile1.js

function walk(f, node) {
  f(node);
  node = node.firstChild;
  while (node) {
    walk(f, node);
    node = node.nextSibling;
  }
}

function parseNode(node) {
  if (node.nodeType !== Node.ELEMENT_NODE) { return }

  var style = window.getComputedStyle(node);
  var fontFamily = style.getPropertyValue("font-family");
  var fontWeight = style.getPropertyValue("font-weight");

  console.log(node.tagName, fontFamily, fontWeight);
}

walk(parseNode, document.body);