cheat sheets.

Element Functions	 

$()
obj = $('elementID');	
  Get the html element with the ID of elementID
objArray = $("element1","element2");
  Get an array containing multiple elements
document.getElementsByClassName("theclass");
  Get an array containing all elements with the class theclass
Element.removeClassName(elementID,theclass); 
  Remove the class from the element.
Element.addClassName(elementID,theclass);	
  Add the class theclass to the element  
new Insertion.Before(elementid,text here);	
  Inserts the text directly before the elementid element.
    text here<span id=elementid>Original</span>
new Insertion.Top(elementid,text here);	
  Inserts the text inside the element at the top:
    <span id=elementid>text here Original</span>
new Insertion.Bottom(elementid, text here);	
  Inserts the text inside the element at the bottom:
   <span id=elementid>Original text here</span>
new Insertion.After(elementid,text here);	
  Inserts the text directly after the elementid element.
    <span id=elementid>Original</span>text here
$(element1,element2).each( function (theobj){
  alert(theobj.innerHTML);
});	
  Traverse through the array using the .each syntax similar to ruby.
Element.hide(elementid);	
  Hides the element
Element.show(elementid);	
  Shows the element
Element.toggle(elementid);	
  Toggles the show/hide status of an element
Element.remove(elementid);	
  Remove an element from the page

 	 
Form Functions	 

$F(fieldname);
  Return the value of the form element, whether it is a text input, textarea,
  select box or checkbox. If it is a checkbox, it will return undefined if
  unchecked. Radio groups dont work.
Form.getElements(formID);
  Returns an array of all the form elements for form formID
Form.serialize(formID);
  Returns a formatted URL containing all the elements in the form, similar to
  &field=value&field2=othervalue
Form.focusFirstElement(formID);	
  Will set focus on the first form element.

 	 
Exception Handling	 

Try.these(
       function(){  
            // errors 
       }, 
       function(){
            // other stuff
       }
);
  Allows you to execute the second function if the first one fails. 
  Kinda like try/catch, except it doesn't make any sense.

                       	 
Ajax

function ajaxMe( theUrl, data ){
   var ajaxRequest = new Ajax.Request(
     theUrl,{method: post, parameters: data, onComplete: theResponse});
}

function theResponse(origRequest){
    alert(origRequest.responseText);
}

Classes

var Butter = Class.create({
  initialize: function(brand) {
    this.brand = brand;
    this.melted = false;
  },
  melt: function() {
    this.melted = true;
  }
})
var parkay = new Butter('Parkay');

  Prototype gives you a way to create classes. If you want, you
  can define an initialize function that will be called when
  instances of the class are created.