When you need to include multiple nested single quotes within a string of javascript to be executed, escape single quotes with a back slash as needed.

Example from within an .rhtml template

hide_warning = "window.setTimeout('Effect.BlindUp($(\\'flash_box\\'), {duration:.3})', #{@warning_timeout ||= 8000})"

In this example, Double backslashes are required since the blackslash itself needs to be escaped and included within the string of js to be executed by windown.setTimeout().

Simply call the event of the object.

<select id='element_id' onChange="some_javascript_func">

<a href="#" onclick="$('element_id').onchange();">

Note that this uses Prototype's $ function to find the element.

More details here:
http://tinyurl.com/2b45me

// http://www.sitepoint.com/blogs/2007/07/11/insert-in-place-without-documentwrite/

// So, given a syndication script with a fixed ID:
<script type="text/javascript" id="syndication" src="syndication.js">script> 

// We can go from oldskool nastiness like this:
document.write('
Here is some syndicated content.'); 

// To modern loveliness like this:

var newcontent = document.createElement('p'); 
newcontent.id = 'syndicated-content'; 
newcontent.appendChild(document.createTextNode('Here is some syndicated content.')); 
var scr = document.getElementById('syndication'); 
scr.parentNode.insertBefore(newcontent, scr); 

// We could even go a step further and remove the <script> ID, but in that case we would need a concrete method for identifying the specific element. We could do that by knowing its SRC:

var scripts = document.getElementsByTagName('script'); 
for(var i=0; i<scripts.length; i++) 
{ 
  if(scripts[i].src == 'http://www.mydomain.com/syndication.js') 
  { 
    //scripts[i] is the one 
    break; 
  } 
}

This gives you a new event (onDOMReady).

Object.extend(Event, {
  _domReady : function() {
    if (arguments.callee.done) return;
    arguments.callee.done = true;

    if (this._timer)  clearInterval(this._timer);
    
    this._readyCallbacks.each(function(f) { f() });
    this._readyCallbacks = null;
},
  onDOMReady : function(f) {
    if (!this._readyCallbacks) {
      var domReady = this._domReady.bind(this);
      
      if (document.addEventListener)
        document.addEventListener("DOMContentLoaded", domReady, false);
        
        /*@cc_on @*/
        /*@if (@_win32)
            document.write("
Create DB | 
Simple Add Record | 
Parameterized Add Record | 
Simple Select | 
Parameterized Select |

// To include the nice little live-updated Digg widget

<script src="http://digg.com/tools/diggthis.js" type="text/javascript">script>

Technorati tracks when other bloggers link to your blog and this widget makes it possible for you to display the number of links on every blog post. We call them "reactions" to encourage readers to follow the conversation. To add the widget, copy and paste the code below into your blog's template.

<script src="http://embed.technorati.com/linkcount" type="text/javascript">script>
//technorati.com/search/<txp:permlink />" rel="linkcount">View blog reactions

Code to dynamically download and include JS

/** include - including .js files from JS - [email protected] - 2005-02-09    **
 ** Code licensed under Creative Commons Attribution-ShareAlike License      **
 ** http://creativecommons.org/licenses/by-sa/2.0/                           **/
var hIncludes = null;
function include(sURI)
{
  if (document.getElementsByTagName)
  {
    if (!hIncludes)
    {
      hIncludes = {};
      var cScripts = document.getElementsByTagName("script");
      for (var i=0,len=cScripts.length; i < len; i++)
        if (cScripts[i].src) hIncludes[cScripts[i].src] = true;
    }
    if (!hIncludes[sURI])
    {
      var oNew = document.createElement("script");
      oNew.type = "text/javascript";
      oNew.src = sURI;
      hIncludes[sURI]=true;
      document.getElementsByTagName("head")[0].appendChild(oNew);
    }
  }
}

Suppose that you don't know the exact class that should be created until runtime. In the case of JavaScript, this may be due to browser differences. The best example of this today is in creating XMLHttp objects. A lot of times, you'll see code that looks like this:

if (typeof XMLHttpRequest != "undefined") {
    return new XMLHttpRequest();
} else if (typeof window.ActiveXObject != "undefined") {
    return new ActiveXObject("MSXML2.XMLHttp");
}

Clearly, you don't want to repeat this code every time you need to create a new XMLHttp object.

The factory pattern involves having a function (or an object with a method) that returns the appropriate object. Developers need not know which object is being returned since the interface will be the same no matter what. You need only call the function and know that the correct object will be returned. For example:

function XMLHttpFactory() {
}

XMLHttpFactory.createXMLHttp = function () {
    if (typeof XMLHttpRequest != "undefined") {
        return new XMLHttpRequest();
    } else if (typeof window.ActiveXObject != "undefined") {
        return new ActiveXObject("MSXML2.XMLHttp");
    }
} 

With this defined, developers can now use a single method call to create the object that will work for their environment:

var oXMLHttp = XMLHttpFactory.createXMLHttp();

function MyClass() {
   if (MyClass.caller != MyClass.getInstance) {
       throw new Error("There is no public constructor for MyClass.");
   }

   this.myproperty = "hello world";
}

MyClass.__instance__ = null;  //define the static property

MyClass.getInstance = function () {
    if (this.__instance__ == null) {
        this.__instance__ = new MyClass();
    }

    return this.__instance__;
}

Checking for the MyClass.caller != MyClass.getInstance in MyClass constructor will suppress the ability of the developer to do this:

var oMyObject = new MyClass();