20100507-hoge.js

function processLine(e) {
  var re = {
    'tumblr': /^http:\/\/[^.]+\.tumblr\.com\/post\//,
    'nicovideo': /^http:\/\/(www\.nicovideo\.jp\/watch|nico\.ms)\/[sn]m(\d+)/,
    'youtube': /^http:\/\/((www\.)?youtube\.com\/|youtu\.be\/).*v=([a-zA-Z0-9\-]+)/
  };

  var line = e.target;
  if (line.getAttribute('class') != 'line text') return;
  var anchor = line.getElementsByClassName('url').item(0);
  if (!anchor) return;
  var uri = anchor.textContent;
  if (re.tumblr.test(uri)) {
    var api_uri = uri + '/xml';
    h(api_uri, function(req) {
      var doc = req.responseXML;
      var image_uri = doc.getElementsByTagName('photo-url').item(0).textContent;
      add_inline_image(line, image_uri, uri);
    });
  } else if (re.nicovideo.test(uri)) {
    var video_id = RegExp.$1;
    var image_uri = 'http://tn-skr' + (video_id * 1) % 4 + 1 + '.smilevideo.jp/smile?i=' + id;
    add_inline_image(line, image_uri, uri);
  } else if (re.youtube.test(uri)) {
    var video_id = RegExp.$3;
    var image_uri = 'http://i.ytimg.com/vi/' + video_id + '/0.jpg';
    add_inline_image(line, image_uri, uri);
  }
}

function add_inline_image(line, image_uri, uri) {
  line.innerHTML = line.innerHTML + [
    '<br><a href="',
    uri,
    '"><img src="',
    image_uri,
    '" class="inlineimage"></a>'].join('');
}


function h(api_uri, func){
  var req = new XMLHttpRequest();
  req.open('get', api_uri, false);
  req.send(null);
  if (req.status == 200)
    func(req);
}

document.addEventListener('DOMNodeInserted', processLine, true);