Atomizer: Small embeddable JavaScript web client for Atom feeds.

atomizer.js

/*jslint browser: true, indent: 2 */

// Atomizer: Small embeddable JavaScript web client for Atom feeds (RFC 4287).
//
// Generates unordered lists or tables which can be inserted anywhere on 
// the page using innerHTML.
//
// The Atom feed needs to be on the same hostname, port and protocol as the 
// web page, because of browser security policies. 
// See <http://en.wikipedia.org/wiki/Same_origin_policy>
//
// Does not handle RSS feeds. Generate Atom, it's better.
//
// Guaranteed 100% framework-free. Placed in the public domain to use as you 
// like.

var parse8601;
// If the browser is ECMA-262 v5 capable and can parse ISO8601 timestamps,
// use its native parse code for speed. Otherwise, use some ugly JavaScript.
if (isNaN(Date.parse("1968-10-15T13:45:20Z"))) {
  // Adapted from http://delete.me.uk/2005/03/iso8601.html
  parse8601 = function (string) {
    "use strict";
    var offset = 0, result = new Date(), time,
      regexp = "([0-9]{4})(-([0-9]{2})(-([0-9]{2})" +
      "(T([0-9]{2}):([0-9]{2})(:([0-9]{2})(\\.([0-9]+))?)?" +
      "(Z|(([-+])([0-9]{2}):?([0-9]{2})))?)?)?)?",
      d = string.match(new RegExp(regexp)),
      date = new Date(d[1], 0, 1);
    if (d[3]) { date.setMonth(d[3] - 1); }
    if (d[5]) { date.setDate(d[5]); }
    if (d[7]) { date.setHours(d[7]); }
    if (d[8]) { date.setMinutes(d[8]); }
    if (d[10]) { date.setSeconds(d[10]); }
    if (d[12]) { date.setMilliseconds(Number("0." + d[12]) * 1000); }
    if (d[14]) {
      offset = (Number(d[16]) * 60) + Number(d[17]);
      offset *= ((d[15] === '-') ? 1 : -1);
    }
    offset -= date.getTimezoneOffset();
    time = (Number(date) + (offset * 60 * 1000));
    result.setTime(Number(time));
    return result;
  };
} else {
  parse8601 = function (string) {
    "use strict";
    return new Date(Date.parse(string));
  };
}

// var f = new Feed();
// or
// var f = new Feed(atom-url);
//
// Feed object then has the following methods:
//
// .add(url) - add in entries from a second Atom feed.
// .sort()   - sort entries in object by descending update date.
// .truncate(N) - limit to top N entries.
// .newdays  - number of days for which entries should show 'New' in red,
//             0 to disable feature (default).
// .updated  - JavaScript updated date from feed.
// .cssclass - CSS class to use when generating H3 header.
// .toUL()   - return HTML for an unordered list of the entries.
// .toTABLE() - return HTML for a table of the entries.

// Define Feed to be the result of evaluating an anonymous function which
// defines a bunch of stuff internally, hidden to the environment outside
// it, then returns the Feed object which we want to make visible.
var Feed = (function () {
  "use strict";

  var MONTHS = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep',
    'Oct', 'Nov', 'Dec'], Entry, Feed, ONE_DAY_MS = 86400000, normalize,
    dateToString, dateTimeToString;

  dateToString = function (x) {
    return x.getDate() + "\u00A0" + MONTHS[x.getMonth()] + "\u00A0" +
      x.getFullYear();
  };

  dateTimeToString = function (x) {
    var z = x.getTimezoneOffset(),
      minus = (z < 0 ? '+' : '-'),
      hh = Math.abs(z / 60),
      mm = Math.abs(z) % 60,
      zone = minus + ('0' + hh).slice(-2) + ('0' + mm).slice(-2);
    return dateToString(x) + " " +
      x.getHours() + ":" + x.getMinutes() + "\u00A0" + zone;
  };

  // Internet Explorer is supposed to have IXMLDOMElement.normalize()
  // but it doesn't work, "Object doesn't support this property or method"
  normalize = function (node) {
    var child, nextChild;
    if (node.normalize) {
      node.normalize();
      return;
    }
    child = node.firstChild;
    while (child) {
      if (child.nodeType === 3) {
        nextChild = child.nextSibling;
        while (nextChild && nextChild.nodeType === 3) {
          child.appendData(nextChild.data);
          node.removeChild(nextChild);
          nextChild = child.nextSibling;
        }
      } else {
        normalize(child);
      }
      child = child.nextSibling;
    }
  };

  // Entry object represents an individual entry (story) in an Atom feed.
  Entry = function (entrynode) {
    var kids, node, i;
    kids = entrynode.childNodes;
    for (i = 0; i < kids.length; i += 1) {
      node = kids[i];
      switch (node.nodeName) {
      case 'title':
        normalize(node.firstChild);
        this.title = node.firstChild.nodeValue;
        break;
      case 'link':
        this.link = node.getAttribute('href');
        break;
      case 'updated':
        this.updated = parse8601(node.firstChild.nodeValue);
        break;
      case 'summary':
        normalize(node.firstChild);
        this.summary = node.firstChild.nodeValue;
        break;
      }
    }
  };

  Entry.prototype.toLI = function (newdays) {
    var txt, isnew = '';
    if (this.updated !== undefined && newdays !== 0 &&
        (new Date() - this.updated) < newdays * ONE_DAY_MS) {
      isnew = "<span style='color: red; font-size: smaller;'>New</span> ";
    }
    txt = "<li>" + isnew + "<a href='" + this.link + "'>" + this.title + "</a>";
    if (typeof this.summary === 'string') {
      txt += "&mdash;" + this.summary;
    }
    return txt + "</li>";
  };

  Entry.prototype.toTR = function () {
    return "<tr><td class='date'>" + dateToString(this.updated) + 
      "</td><td><a href='" + this.link + "'>" + this.title + "</a></td></tr>";
  };

  // Create a Feed object to represent one or more Atom feeds
  Feed = function (url) {
    this.entries = [];
    this.base = '';
    this.newdays = 0;
    this.updated = new Date();
    if (typeof url === 'string') {
      this.add(url);
    }
    this.cssclass = 'bar-green-dark';
  };

  // Sort into descending order of update time/date
  Feed.prototype.sort = function () {
    var byupdated = function (a, b) {
      return b.updated - a.updated;
    };
    this.entries.sort(byupdated);
  };

  Feed.prototype.truncate = function (n) {
    if (this.entries.length > n) {
      this.entries = this.entries.slice(0, n - 1);
    }
  };

  // Add data from an atom feed into the Feed object.
  // If you use a URL with a path, subsequent pathless URLs are considered
  // to have the same base path. e.g.
  //   foo.add('http://www.example.com/something/feed.xml');
  //   foo.add('feed2.xml') => uses base path from line above
  /*jslint regexp: true */
  Feed.prototype.add = function (url) {
    var http = new XMLHttpRequest(), dom, feed, node, i, kids, entry,
      entries = [], updated, base = url.replace(/^[^\/]*/, '');
    /*jslint regexp: false */
    if (url.lastIndexOf('/') < 0) {
      url = this.base + url;
    } else {
      if (this.base === '') {
        this.base = base;
      }
    }
    http.open("GET", url, false);
    http.send();
    dom = http.responseXML;
    feed = dom.documentElement;
    if (feed.nodeName !== 'feed') {
      return;
    }
    kids = feed.childNodes;
    for (i = 0; i < kids.length; i += 1) {
      node = kids[i];
      switch (node.nodeName) {
      case 'title':
        normalize(node.firstChild);
        this.title = node.firstChild.nodeValue;
        break;
      case 'updated':
        normalize(node.firstChild);
        updated = parse8601(node.firstChild.nodeValue);
        break;
      case 'entry':
        entry = new Entry(node);
        if (this.mrentry === undefined || this.mrentry < entry.updated) {
          this.mrentry = entry.updated;
        }
        entries.push(new Entry(node));
        break;
      }
    }
    if (this.mrupdate === undefined || this.mrupdate < updated) {
      this.mrupdate = updated;
      this.updated = updated;
    }
    if (entries.length > 0) {
      this.entries = this.entries.concat(entries);
    }
  };

  // Builds an unordered list with title to drop into a web page.
  // See http://www.quirksmode.org/dom/innerhtml.html
  // and don't use DOM to build page elements.
  Feed.prototype.toUL = function () {
    var html = ["<h3 class='" + this.cssclass + "'>" + this.title + "</h3><ul>"], i;
    if (this.entries.length === 0) {
      return "";
    }
    for (i = 0; i < this.entries.length; i += 1) {
      html.push(this.entries[i].toLI(this.newdays));
    }
    html.push("</ul>");
    if (this.mrentry !== undefined) {
      html.push("<p class='note'>Updated " + dateToString(this.mrentry) + "</p>");
    }
    return html.join('');
  };

  Feed.prototype.toTABLE = function () {
    var html = ["<table class='feed'><caption>" + this.title + 
      "</caption><tbody>"], i;
    if (this.entries.length === 0) {
      return "";
    }
    for (i = 0; i < this.entries.length; i += 1) {
      html.push(this.entries[i].toTR());
    }
    html.push("</tbody></table>");
    return html.join('');
  };

  return Feed;
}());