As with most my other crib sheet pages, this is a quick reference for javascript for myself, which I am leaving available on the net. It has things I need from time to time, and is not meant to be a comprehensive resource.

It is a combination of my own discoveries as well as information gathered around the net. One large source for this Douglas Crockford's video classes on javascript and DOM available at



Arrays are based on objects with some special features added. They however lose this specialness when extended so don't.


DOM Reference:

Set Class & Style Values

node.className = ... = ...

Find current values

IE: node.currentStyle.stylename
Others: document.defaultView().getComputedStyle( node, "" ).getPropertyValue( stylename );

Creating Non-Table Elements

var n = document.createElement(tagName);
var t = document.createTextNode( text );

Creating Table Elements

trObj = table.insertRow( pos );
tdObj = tableRow.insertCell( pos );      
Unlike node creation, these actually insert the object.
A pos of -1 inserts at the end.

Adding / Removing nodes to the tree

parent.appendChild( new );
parent.insertBefore( new, child );

parent.replaceChild( new, old );

parent.removeChild( old );
Parent can be found as child.parentNode


blur, change, keydown, keypress, keyup, reset, submit, focus click, dblclick, mousedown, mousemove, mouseout, mouseover, mouseup

Setting handler

Handler template

Gets common variables in a browser compatible way

function handler(e) {
    if (!e) e = event;
    var target = || e.srcElement;

Cancel Event (bubbling)

e.cancelBubble = true;
    if ( e.stopPropogation ) {

Cancel Default Action

e.returnValue = false;
if ( e.preventDefault ) {
return false;

An exception can be any created object with the fields name and message. When checking exceptions, the name field can be used to find the type you are interested in.

Names used with in Javascript, which can be created using new Name(msg)

Error, EvalError, RangeError, SyntaxError, TypeError, URIError

Creating your own

throw { name:"MyError", message:"Failed to ..." };
for ... in

The in variant of the for statement is very useful for going over all value on an objected. However when doing so it also returns any methods or properties from Object or any other object which it inherited from. To prevent this and only see values on the main object use the following template.

for ( name in ob ) {
    if ( ob.hasOwnProperty( name ) ) {

Javascript has lousy name space support. There is alot of room for overlap in the global general name space. To alleviate this, its reccomended you create your own space and place your own variables with in it.


Values returned from typeof operator

Variable Type Returned
array "object"
boolean "boolean"
function "function"
null "object"
number "number"
object "object"
string "string"
underfined "undefined"
Other References