collection.js

// Taken from from underscore.js http://documentcloud.github.com/underscore
var breaker = {};
var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;

var
    nativeForEach      = ArrayProto.forEach,
    nativeMap          = ArrayProto.map,
    nativeReduce       = ArrayProto.reduce,
    nativeReduceRight  = ArrayProto.reduceRight,
    nativeFilter       = ArrayProto.filter,
    nativeEvery        = ArrayProto.every,
    nativeSome         = ArrayProto.some,
    nativeIndexOf      = ArrayProto.indexOf,
    nativeLastIndexOf  = ArrayProto.lastIndexOf,
    nativeIsArray      = Array.isArray,
    nativeKeys         = Object.keys,
    nativeBind         = FuncProto.bind;

// The cornerstone, an `each` implementation, aka `forEach`.
// Handles objects with the built-in `forEach`, arrays, and raw objects.
// Delegates to **ECMAScript 5**'s native `forEach` if available.
var each = function(obj, iterator, context) {
  if (obj == null) return;
  if (nativeForEach && obj.forEach === nativeForEach) {
    obj.forEach(iterator, context);
  } else if (obj.length === +obj.length) {
    for (var i = 0, l = obj.length; i < l; i++) {
      if (iterator.call(context, obj[i], i, obj) === breaker) return;
    }
  } else {
    for (var key in obj) {
      if (hasOwnProperty.call(obj, key)) {
        if (iterator.call(context, obj[key], key, obj) === breaker) return;
      }
    }
  }
};

// Determine if at least one element in the object matches a truth test.
// Delegates to **ECMAScript 5**'s native `some` if available.
// Aliased as `any`.
var any = function(obj, iterator, context) {
  iterator || (iterator = _.identity);
  var result = false;
  if (obj == null) return result;
  if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
  each(obj, function(value, index, list) {
    if (result || (result = iterator.call(context, value, index, list))) return breaker;
  });
  return !!result;
};

// Return the first value which passes a truth test. Aliased as `detect`.
var find = function(obj, iterator, context) {
 var result;
 any(obj, function(value, index, list) {
   if (iterator.call(context, value, index, list)) {
     result = value;
     return true;
   }
 });
 return result;
};

module.exports = {
 any: any
, each: each
, find: find
};