save website with nodejs

Here, have a look:
How can I save objects to files in Node.js?[^]

To serialize your objects to a JSON string:

var str = JSON.stringify(object)

To read it back as an object. (The string can be written to file):

var obj = JSON.parse(string)

For example an object like this:

var p = new Foo();
p.Bar = "Terry"
var s = JSON.stringify(p)
// write s to file, get => { "Bar" : "Terry" }
// read s from file and turn back into an object:
var p = JSON.parse(s);

Further, this is an interesting read: NodeJS and Callbacks[^]