// ==UserScript==
// @name          Show links to headings
// @namespace     http://fg-180.katamayu.net/script
// @description    kinmo-
// @include       http://*
// ==/UserScript==

(function() {
  function addLinkTo(tagName) {
    var elements = document.getElementsByTagName(tagName);

    for (var i = 0; i < elements.length; i++) {
      if (elements[i].id) {
        var a = document.createElement('a');
        a.appendChild(document.createTextNode('_'));
        a.href = "#" + elements[i].id;
        elements[i].insertBefore(a, elements[i].firstChild);
      }
    }
  }

  addLinkTo('h1');
  addLinkTo('h2');
  addLinkTo('h3');
  addLinkTo('h4');
  addLinkTo('h5');
})();