var vs this in Javascript object

Question

I\'m developing a web framework for node.js. here is the code;

function Router(request, response) {
        this.routes = {};

        var parse = require(         


        

Answer 1

Using var in the constructor is usually used for private variable while using this. is used for public variable.

Example with this. :

function Router() {
    this.foo = "bar";

    this.foobar = function () {
         return this.foo;
    }
}

var r = new Router();
r.foo // Accessible

Example with var :

function Router() {
    var _foo = "bar";

    this.foobar = function () {
         return _foo;
    }
}

var r = new Router();
r._foo // Not accessible