A proper clone

clone.js

// example: http://jsfiddle.net/QVqHs/

function clone(o) {
    return Object.create(
        Object.getPrototypeOf(o), 
        getOwnPropertyDescriptors(o)
    )
}

function getOwnPropertyDescriptors(o) {
    return Object.keys(o).reduce(getPropertyDescriptor.bind(o), {})
}

function getPropertyDescriptor(acc, key) {
    acc[key] = Object.getOwnPropertyDescriptor(this, key)
    return acc
}

Nice trick passing a "third argument" to getPropertyDescriptor.