how make multiple requests in node js

I have an array of 4 urls and each url has json data. how to loop through urls

ex :
urls =[ "http://url1.com", "http://url2.com", "http://url3.com", "http://url4.com"];

each url has json one student information like

              { date: 08/05/2014
                 studentname: 'xyz'
                 student marks:[
                              maths:80
                              science:60 
                               ]
              }

now i want to loop through all 4 urls in this case 4 students information to get all student marks at once(means some thing like all information into one object]so later i can parse and find out which student has got the highest marks or lowest marks ? how this can be done in node.js ?

https://github.com/mikeal/request https://github.com/caolan/async#map

var async = require('async');
var request = require('request');

async.map(urls, function(url, callback) {
    request(url, function(err, response, body) {
        callback(err, body);
    })
}, function(err, students){
    if(err) {
        return console.error(err);
    }

    //Do sth. with students array
});