cookies.md

cookies

I want to persist data between req/res pairs from the same client

Using cookies you cam get() and set() HTTP cookies on a req / res pair. cookies also allows you to handle options like signed cookies and setting the domain / http only flag. Cookies will stick in the http client and will be send again with the next request by that client.

var http = require("http")
var cookies = require("cookies")

http.createServer(function (req, res) {
    var cookies = Cookies(req, res)

    // fetch value out of cookie
    var count = Number(cookies.get("count")) || 0
    count++
    // store value in cookie
    cookies.set("count", String(count))

    res.end("you have watched this page " + count + " times")
}).listen(8080)

Alternatively by hand:

var http = require("http")

http.createServer(function (req, res) {
    var cookie = req.headers.cookie || ""

    // parse cookie out
    var pairs = cookie.split(";")
    var obj = {}
    pairs.forEach(function (pair) {
        var parts = pair.split("=")
        obj[parts[0].trim()] = parts[1].trim()
    })

    var count = Number(obj.count) || 0
    count++

    // serialize cookie
    res.setHeader("Set-Cookie", "count=" + count)

    res.end("you have watched this page " + count + " times")
}).listen(8080)

Note that using cookies gives you a more forgiving parser & serializer as well as it handling all options & signed cookies.