javascript-patterns/design-patterns/proxy.html at master · cyberpython/javascript-patterns · GitHub

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<!doctype html>
<html lang="en">
<head>
<title>JavaScript Patterns</title>
<meta charset="utf-8">
<style>
  img {float: left; padding-right: 7px;}
  div {padding: 7px; border: 1px solid #ccc; background: #eee; width: 400px;}
  h2 {margin: 0;}
  span {text-decoration: underline; cursor: pointer;}
  body {padding: 21px; font-size: 105%; font-family: Helvetica;}
  input {margin-right: 7px;}
  a {color: blue;}
</style>
</head>
<body>
<h1>Dave Matthews vids</h1>
<p><span id="toggle-all">Toggle Checked</span></p>
<ol id="vids">
  <li><input type="checkbox" checked><a href="http://new.music.yahoo.com/videos/--2158073">Gravedigger</a></li>
  <li><input type="checkbox" checked><a href="http://new.music.yahoo.com/videos/--4472739">Save Me</a></li>
  <li><input type="checkbox" checked><a href="http://new.music.yahoo.com/videos/--45286339">Crush</a></li>
  <li><input type="checkbox" checked><a href="http://new.music.yahoo.com/videos/--2144530">Don't Drink The Water</a></li>
  <li><input type="checkbox" checked><a href="http://new.music.yahoo.com/videos/--217241800">Funny the Way It Is</a></li>
  <li><input type="checkbox" checked><a href="http://new.music.yahoo.com/videos/--2144532">What Would You Say</a></li>
</ol>

<script>
/* Title: Proxy
 Description: provides a placeholder for another object to control access, reduce cost, and reduce complexity
*/

var $ = function (id) {
  return document.getElementById(id);
};

var http = {
  makeRequest: function (ids, callback) {
    var url = 'http://query.yahooapis.com/v1/public/yql?q=',
        sql = 'select * from music.video.id where ids IN ("%ID%")',
        format = "format=json",
        handler = "callback=" + callback,
        script = document.createElement('script');

        sql = sql.replace('%ID%', ids.join('","'));
        sql = encodeURIComponent(sql);

        url += sql + '&' + format + '&' + handler;
        script.src = url;

        document.body.appendChild(script);
  }
};

var proxy = {
  ids: [],
  delay: 50,
  timeout: null,
  callback: null,
  context: null,
  makeRequest: function (id, callback, context) {

    // add to the queue
    this.ids.push(id);

    this.callback = callback;
    this.context  = context;

    // set up timeout
    if (!this.timeout) {
      this.timeout = setTimeout(function () {
        proxy.flush();
      }, this.delay);
    }
  },
  flush: function () {
    http.makeRequest(this.ids, "proxy.handler");
    // clear timeout and queue
    this.timeout = null;
    this.ids = [];

  },
  handler: function (data) {
    var i, max;

    // single video
    if (parseInt(data.query.count, 10) === 1) {
      proxy.callback.call(proxy.context, data.query.results.Video);
      return;
    }

    // multiple videos
    for (i = 0, max = data.query.results.Video.length; i < max; i += 1) {
      proxy.callback.call(proxy.context, data.query.results.Video[i]);
    }
  }
};


var videos = {
  getPlayer: function (id) {
    return '' +
    '<object width="400" height="255" id="uvp_fop" allowFullScreen="true">' +
      '<param name="movie" value="http://d.yimg.com/m/up/fop/embedflv/swf/fop.swf"\/>' +
      '<param name="flashVars" value="id=v' + id + '&amp;eID=1301797&amp;lang=us&amp;enableFullScreen=0&amp;shareEnable=1"\/>' +
      '<param name="wmode" value="transparent"\/>' +
      '<embed ' +
        'height="255" ' +
        'width="400" ' +
        'id="uvp_fop" ' +
        'allowFullScreen="true" ' +
        'src="http://d.yimg.com/m/up/fop/embedflv/swf/fop.swf" ' +
        'type="application/x-shockwave-flash" ' +
        'flashvars="id=v' + id  + '&amp;eID=1301797&amp;lang=us&amp;ympsc=4195329&amp;enableFullScreen=1&amp;shareEnable=1"' +
      '\/>' +
    '<\/object>';
  },

  updateList: function (data) {
    var id,
        html = '',
        info;

    if (data.query) {
      data = data.query.results.Video;
    }
    id = data.id;
    html += '<img src="' + data.Image[0].url + '" width="50" \/>';
    html += '<h2>' + data.title + '<\/h2>';
    html += '<p>' + data.copyrightYear + ', ' + data.label + '<\/p>';
    if (data.Album) {
      html += '<p>Album: ' + data.Album.Release.title + ', ' + data.Album.Release.releaseYear + '<br \/>';
    }
    html += '<p><a class="play" href="http://new.music.yahoo.com/videos/--' + id + '">&raquo; play<\/a><\/p>';
    info = document.createElement('div');
    info.id = "info" + id;
    info.innerHTML = html;
    $('v' + id).appendChild(info);
  },

  getInfo: function (id) {
    var info = $('info' + id);

    if (!info) {
      proxy.makeRequest(id, videos.updateList, videos);
      return;
    }

    if (info.style.display === "none") {
      info.style.display = '';
    } else {
      info.style.display = 'none';
    }
  }
};


$('vids').onclick = function (e) {
  var src, id;

  e = e || window.event;
  src = e.target || e.srcElement;

  if (src.nodeName.toUpperCase() !== "A") {
    return;
  }

  if (typeof e.preventDefault === "function") {
    e.preventDefault();
  }
  e.returnValue = false;

  id = src.href.split('--')[1];

  if (src.className === "play") {
    src.parentNode.innerHTML = videos.getPlayer(id);
    return;
  }

  src.parentNode.id = "v" + id;
  videos.getInfo(id);
};

$('toggle-all').onclick = function (e) {

  var hrefs,
      i,
      max,
      id;

  hrefs = $('vids').getElementsByTagName('a');
  for (i = 0, max = hrefs.length; i < max; i += 1) {
    // skip play links
    if (hrefs[i].className === "play") {
      continue;
    }
    // skip unchecked
    if (!hrefs[i].parentNode.firstChild.checked) {
      continue;
    }

    id = hrefs[i].href.split('--')[1];
    hrefs[i].parentNode.id = "v" + id;
    videos.getInfo(id);
  }
};

// reference
// http://www.addyosmani.com/resources/essentialjsdesignpatterns/book/#proxypatternjquery
// http://shop.oreilly.com/product/9780596806767.do?sortby=publicationDate
</script>
</body>
</html>