How can I access and process nested objects, arrays or JSON?

I have a nested data structure containing objects and arrays. How can I extract the information, i.e. access a specific or multiple values (or keys)?

For example:

var data = {
    code: 42,
    items: [{
        id: 1,
        name: 'foo'
    }, {
        id: 2,
        name: 'bar'
    }]
};

How could I access the name of the second item in items?