test programmatic npm install

npminstall.js

var npm = require('npm');
npmInstall(['http://dl.dropbox.com/u/3098507/sample.tar.gz'], function () {
  console.log('yay');
});

/* 
programmatically install some libs with npm
working in OSX but not windows
*/
function npmInstall(libs, callback){
  npm.load({}, function (er) {
    if (er) throw new Error(er);
    npm.commands.install(libs, function (er, data) {
      if (er) throw new Error(er);
      callback.call(this);
    });
  });
}