git.r.bdr.sh - rbdr/dotfiles/blob

   1 // Inspired by Underscore's groupBy:
   2 // http://documentcloud.github.com/underscore/#groupBy
   3
   4 'use strict';
   5
   6 var callable = require('../../object/valid-callable')
   7   , value    = require('../../object/valid-value')
   8
   9   , forEach = Array.prototype.forEach, apply = Function.prototype.apply;
  10
  11 module.exports = function (cb/*, thisArg*/) {
  12         var r;
  13
  14         (value(this) && callable(cb));
  15
  16         r = {};
  17         forEach.call(this, function (v) {
  18                 var key = apply.call(cb, this, arguments);
  19                 if (!r.hasOwnProperty(key)) r[key] = [];
  20                 r[key].push(v);
  21         }, arguments[1]);
  22         return r;
  23 };