Packages used along some package

gistfile1.txt

$ node index.js gl-shader
11      gl-buffer
11      gl-vao
10      gl-texture2d
10      ndarray
6       glslify
6       a-big-triangle
5       gl-fbo
5       gl-mat4
5       typedarray-pool
4       ndarray-ops
3       barycentric
3       colormap
3       binary-search-bounds
3       glsl-specular-cook-torrance
3       normals

gistfile2.txt

$ node index.js dom-events
5       inherits
3       events
3       xtend
3       domready
2       bower
2       insert-css
2       hapi
2       hoek
2       request
2       handlebars
2       browserify
2       brfs
2       moment
2       mouse-event-offset
2       mkdirp

gistfile3.txt

$ node index.js glslify
19      gl-buffer
18      gl-vao
15      gl-mat4
10      gl-texture2d
9       ndarray
6       gl-matrix
6       gl-shader
5       a-big-triangle
5       typedarray-pool
4       bit-twiddle
4       gl-fbo
4       dup
4       brfs
4       colormap
4       glsl-specular-cook-torrance

index.js

var getDependents = require('npm-get-dependents');
var async = require('async');
var request = require('request');

var packageName = process.argv[2];

getDependents(packageName, function(err, packages) {
  if(err) throw err;
  async.map(packages, getDependencies, function(err, results) {
    if(err) throw err;
    packages = results.reduce(function(memo, result) {
      return memo.concat(result);
    }, []);

    var counts = {};
    packages.forEach(function(packageName) {
      if(!counts[packageName]) counts[packageName] = 1;
      else counts[packageName]++;
    });

    var items = Object.keys(counts)
      .map(function(key) {
        return [key, counts[key]];
      })
      .sort(function(a, b) {
        return b[1] - a[1];
      })

    items
      .slice(0, 15)
      .forEach(function(item) {
        console.log(item[1] + '\t' + item[0]);
      });
  });
});

function getDependencies(packageName, callback) {
  var url = 'http://registry.npmjs.org/' + packageName + '/latest';
  request.get(url, function(err, res) {
    if(err) return callback(err);
    var info = JSON.parse(res.body);
    var deps = Object.keys(info.dependencies);
    callback(null, deps);
  });
}