bugged.js

var StringDecoder = require("string_decoder").StringDecoder

module.exports = body

function body(req, callback) {
    var requestBody = "",
        stringDecoder = new StringDecoder

    req.on("data", addToBody)

    req.on("end", returnBody)

    function addTobody(buffer) {
        requestBody += stringDecoder.write(buffer)
    }

    function returnBody() {
        callback(null, requestBody)        
    }
}

store-in-weakmap.js

var StringDecoder = require("string_decoder").StringDecoder,
    BodyMap = new WeakMap

module.exports = body

function body(req, callback) {
    if (BodyMap.has(req)) {
        callback(null, BodyMap.get(req))
    }
 
    var requestBody = "",
        stringDecoder = new StringDecoder

    req.on("data", addToBody)

    req.on("end", returnBody)

    function addTobody(buffer) {
        requestBody += stringDecoder.write(buffer)
    }

    function returnBody() {
        BodyMap.set(req, requestBody)
        callback(null, requestBody)        
    }
}

store-on-req.js

var StringDecoder = require("string_decoder").StringDecoder

module.exports = body

function body(req, callback) {
    if (req.body) {
        callback(null, req.body)
    }

    var requestBody = "",
        stringDecoder = new StringDecoder

    req.on("data", addToBody)

    req.on("end", returnBody)

    function addTobody(buffer) {
        requestBody += stringDecoder.write(buffer)
    }

    function returnBody() {
        req.body = requestBody
        callback(null, requestBody)        
    }
}