javascript - Using factory methods as alternative to passing anonymous functions -

i watching video on node.js , saw speaker say, prefers instead of using anonymous call backs:

var server = server.createserver(server.createreq(req,res)); 

i think nice named function parameters can passed instead of anonymous function closure.

question 1: implementation of createreq returns anonymous function, wouldn't it?

how better? can see being better because unlike closure @ createserver level, closure @ createreq level more contained - not store reference other unnecessary variables (non req,res).

and speaker said, guess visualize realtionships better between different parts of code.

question 2: there other benefits?

a reason why might want call function returns function may starting multiple servers within same process, , want them share same request handler.

another thing keep in mind each anonymous function must allocated on heap, , incurs garbage collection overhead. using named function instead of anonymous function, can reduce cost.

for example, maybe untested , incomplete example:

var server = server.createserver(handlerequest);  function handlerequest(req, res) {     new client(req, res); }  function client(req, res) {     this.req = req;     this.res = res;      this.body = "";     req.on("data", function (chunk) {         self.ondata(chunk);     }); } client.prototype.ondata = function (chunk) {     this.body += chunk.tostring(); }; 

this example uses small anonymous function bind data event callbacks specific instance of client, other functions named.