Extending an object's properties with another. Kind of a stripped down version of jQuery.extend

extend.js

function extend(destination, source, overwrite) {
	if(typeof overwrite === 'undefined') {
		overwrite = true;
	}
	for(var property in source) {
		if(source.hasOwnProperty(property)) {
			if(!destination[property] || overwrite) {
				destination[property] = source[property];
			}
		}
	}
	return destination;
}