Downloads all files in an array 2 at a time

async-download.js

var fs = require('fs');
var path = require('path');

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

var tasks = {};

var json = { /* your records */ };

json.forEach(function(record) {
	tasks[record.imagefile] = function(callback) {
		request({
			url: 'http://example.com/Clipart/'+record.imagefile,
			encoding: null
		}, function (err, res, data) {
			if (err) return callback(err);
			if (!err && res.statusCode == 200) {
				var f = path.join(process.cwd(), 'downloads/' + record.imagefile);
				fs.writeFile(f, data, function(err) {
					if (err) return callback(err);
					callback(null, f);
				});
			}
		});
	};
});

async.parallelLimit(tasks, 2, function() {
	console.log('done');
});