Merge two JS objects

gistfile1.js

function merge (obj, source) {
	for (prop in source) {
		if (typeof source[prop] === 'object' && typeof obj[prop] === 'object') {
			merge(obj[prop], source[prop])
		}
		else {
			if (obj[prop] === void 0) {
				obj[prop] = source[prop]
			}
		}
	}

	return obj
}