design-patterns/proxy.html

﻿<!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>