I normally put my JavaScript function/classes/other things in namespaces. Namespacing your JavaScript is good, it avoids conflicts between scripts on the page and keeps the global namespace clean. I could go into more detail, but luckily it has been done for me.

Declaring namespaces, and checking they exist before using them is a bit of a pain. You might find yourself doing something like:

if(!window.com) window.com = {};
if(!com.mycompany) com.mycompany = {};
if(!com.mycompany.mypackage) com.mycompany.mypackage = {};

…and then add things to it like:

com.mycompany.mypackage.myfunction = function() { return 138; };

To make things worse, if your webpage includes a different script that uses slightly different namespace, say "com.mycompany.mypackage2" you’ll have to check again that the objects "com" and "com.mycompany" already exist.

The following function allows you to use a namespace, without having to manually go through the throws of checking each "space" exists and creating an empty object for each level.

/**
 * I declare a namespace if it doesn't already exist.
 *
 * @param {String} ns The namespace to create/use
 * @param {Object} parent (Optional) The parent object onto which this namespace will be attached.
 * @return True if the namespace was created successfully.
 * @type Boolean
 */
function namespace(ns, parent) {

	if(!parent) {
		parent = window;
	} else {
		// Parent must be an object
		if(typeof(parent) != 'object') {
			return false;
		}
	}

	var names = ns.split('.');

	if(!names.length) {
		return true;
	}

	var name = names[0];

	if(!parent[name]) {
		parent[name] = {};
	}

	if(names.length > 1) {
		names.shift();
		return namespace(names.join('.'), parent[name]);
	}

	return true;
}

…and is used like so:

namespace('com.mycompany.mypackage');
com.mycompany.mypackage.myfunction = function() { return 138; };