make-selector.js

// Create an absolute jQuery selector for a DOM element.
//
// + el - Element to select.
//
// Returns String selector.
function makeSelector(el) {
  var tag, index, stack = [];

  for (; el.parentNode; el = el.parentNode) {
    tag = el.tagName;

    for (index = 0; el.previousSibling;) {
      el = el.previousSibling;
      if (tag == el.tagName)
        index += 1;
    }

    stack.unshift(tag + ':eq(' + index + ')');
  }

  return stack.join(' > ');
}

// Test makeSelector()
//
// + query - String, jQuery, or DOM Element
//
// Choose the first element in `query` and generate a selector for it.
// Log this to the console.  Report an error if the selector doesn't
// select the original element.
//
// Returns nothing.
function testSelector(query) {
  query = $(query);

  var el = query.get(0),
      selector = makeSelector(el);

  console.log('Made selector', selector, 'for', el);

  var probe = $(selector).get(0);
  if (!probe === el)
    console.error('Expected', el, 'not', probe);
}