bootstrap.js

/**
 * Copyright 2010 Scott Koon
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

var bootstrap = (function() {
	var itemsLoaded = [];
	// maintain a list of items we have already loaded to prevent duplicates
	var bootstrap = function() {
		var args = arguments;
		if (args.length == 0)
			return;

		var scriptSrc = "";
		// figure out if we were passed a script URL, a config object, or an
		// array of script URLs
		var src = args[0];

		if (typeof src === "string") {
			scriptSrc = src;
		} else if (typeof src == "object" || typeof src == "array") {
			processConfigObject(src);
		}

		var head = document.head || document.getElementsByTagName("head")[0];
		var scriptId = args[1] || "script" + Math.floor(Math.random() * 1234);
		var loaded = false;
		var scriptTag = null;
		var callback = callback = args[2] || null;

		function notLoaded(src, type) {
			var nodeList;
			var propToCheck;
			var i = 0, l = itemsLoaded.length;
			while (i < l) {
				if (itemsLoaded[i] == scriptSrc)
					return false;
				i++
			}

			// last ditch effort to see if the script we are trying to load
			// was already loaded using a static script tag.
			if (type === "js") {
				var nodeList = document.getElementsByTagName("script");
				propToCheck = "src";
			} else if (type === "css") {
				var nodeList = document.getElementsByTagName("link");
				propToCheck = "href";
			}

			var nodeArray = (function() {
				var a = [];
				for (var c = nodeList.length; c-- > 0;) {
					if (c in nodeList) {
						a.push(nodeList.c)
					}
				}
				return a
			});
			for (var c = 0, len = nodeArray.length; c < len; c++) {
				if ((propToCheck in nodeArray[c])
						&& nodeArray[c][propToCheck] == src)
					return false;
			}
			return true;

		}

		if (scriptSrc.indexOf(".js") > -1 && notLoaded(scriptSrc, "js")) {
			itemsLoaded.push(scriptSrc);
			scriptTag = createScriptElement(scriptSrc, scriptId);
		}

		if (scriptSrc.indexOf(".css") > -1 && notLoaded(scriptSrc, "css")) {
			itemsLoaded.push(scriptSrc);
			scriptTag = createCssElement(scriptSrc, scriptId);
		}

		if (scriptTag) {
			scriptTag.onload = function() {
				loaded = true;
			}

			scriptTag.onreadystatechange = function() {
				if (!loaded) {
					if (this.readyState == "loaded"
							|| this.readyState == "complete") {
						loaded = true;
					}
				}
			}
			head.appendChild(scriptTag);
		}

		function makeCallback() {
			window.clearInterval(id);
			if (callback != null) {
				callback();
			}
		}

		var id = window.setInterval(function() {
			if (loaded) {
				makeCallback();
			}
		}, 0)
	}

	function createScriptElement(scriptSrc, scriptId) {
		var scriptTag = document.createElementNS(
				'http://www.w3.org/1999/xhtml', 'html:script')
		// document.createElement('script');
		scriptTag.setAttribute("type", "text/javascript");
		scriptTag.src = scriptSrc;
		scriptTag.id = scriptId;
		scriptTag.async = false;
		return scriptTag;
	}

	function createCssElement(scriptSrc, scriptId) {
		var link = document.createElement("link");
		link.rel = "stylesheet";
		link.type = "text/css";
		link.href = scriptSrc;
		link.id = scriptId;
		return link;
	}

	function processConfigObject(config) {
		for ( var script in config) {
			bootstrap(config[script], script);
		}
		;
	}
	return (window.bootstrap = window.$b = bootstrap);
}());

/**
 * Bootstrap is a small library for dynamically loading JavaScript files. It's
 * primary use case is for using in your JS code to load JS files only when they
 * are used. syntax:
 * 
 * bootstrap("script file name.js","id you want the script element to have");
 * 
 * or
 * 
 * $b("script file name.js","id you want the script element to have");
 * 
 * You can also not pass in an id and Bootstrap will assign a random one to your
 * script tag
 * 
 * alternatively, you can pass in a call back function. $b("script file
 * name.js", "id of your element", callBackFunction);
 * 
 * The ID element is also optional if you are not passing in a call back.
 * 
 * If you'd like to specify multiple files, you can either pass in an array
 * containing the names/urls of the scripts you would like to load or you can
 * pass in a config object using the following format: { "{id for the script
 * tag}" : "{name or url for the script}" }
 */