diff --git a/.eslintrc b/.eslintrc
index 73a97e193..b9ca7a590 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -2,7 +2,8 @@
   "env": {
     "browser": true,
     "node": true,
-    "amd": true
+    "amd": true,
+    "es6": true
   },
 
   "rules": {
diff --git a/_arrayHelper.js b/_arrayHelper.js
deleted file mode 100644
index 835b8fbfa..000000000
--- a/_arrayHelper.js
+++ /dev/null
@@ -1,12 +0,0 @@
-const shallowProperty = require('./_shallowProperty');
-const MAX_ARRAY_INDEX = Math.pow(2, 53) - 1;
-const getLength = shallowProperty('length');
-
-// should be iterated as an array or as an object.
-// Related: http://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength
-// Avoids a very nasty iOS 8 JIT bug on ARM-64. #2094
-exports.getLength = getLength;
-exports.isArrayLike = function(collection) {
-  var length = getLength(collection);
-  return typeof length == 'number' && length >= 0 && length <= MAX_ARRAY_INDEX;
-};
\ No newline at end of file
diff --git a/_createIndexFinder.js b/_createIndexFinder.js
deleted file mode 100644
index dd143402a..000000000
--- a/_createIndexFinder.js
+++ /dev/null
@@ -1,26 +0,0 @@
-const getLength = require('./_arrayHelper').getLength;
-
-// Generator function to create the indexOf and lastIndexOf functions.
-module.exports = function(dir, predicateFind, sortedIndex) {
-  return function(array, item, idx) {
-    var i = 0, length = getLength(array);
-    if (typeof idx == 'number') {
-      if (dir > 0) {
-        i = idx >= 0 ? idx : Math.max(idx + length, i);
-      } else {
-        length = idx >= 0 ? Math.min(idx + 1, length) : idx + length + 1;
-      }
-    } else if (sortedIndex && idx && length) {
-      idx = sortedIndex(array, item);
-      return array[idx] === item ? idx : -1;
-    }
-    if (item !== item) {
-      idx = predicateFind(slice.call(array, i, length), _.isNaN);
-      return idx >= 0 ? idx + i : -1;
-    }
-    for (idx = dir > 0 ? i : length - 1; idx >= 0 && idx < length; idx += dir) {
-      if (array[idx] === item) return idx;
-    }
-    return -1;
-  };
-};
\ No newline at end of file
diff --git a/_shallowProperty.js b/_shallowProperty.js
deleted file mode 100644
index 6b46d672e..000000000
--- a/_shallowProperty.js
+++ /dev/null
@@ -1,5 +0,0 @@
-module.exports = function(key) {
-  return function(obj) {
-    return obj != null && key in obj ? obj[key] : void 0;
-  };
-};
\ No newline at end of file
diff --git a/contains.js b/contains.js
index 0a14f2458..2eea517c5 100644
--- a/contains.js
+++ b/contains.js
@@ -1,11 +1,2 @@
-const isArrayLike = require('./_arrayHelper').isArrayLike;
-const values = require('./values');
-const indexOf = require('./indexOf');
-
-// Determine if the array or object contains a given item (using `===`).
 // Aliased as `includes` and `include`.
-module.exports = function(obj, item, fromIndex, guard) {
-  if (!isArrayLike(obj)) obj = values(obj);
-  if (typeof fromIndex != 'number' || guard) fromIndex = 0;
-  return indexOf(obj, item, fromIndex) >= 0;
-};
\ No newline at end of file
+module.exports = require('./includes');
\ No newline at end of file
diff --git a/findIndex.js b/findIndex.js
index 0161818fb..0e2b4bbd7 100644
--- a/findIndex.js
+++ b/findIndex.js
@@ -1,4 +1,19 @@
-const createPredicateIndexFinder = require('./_createPredicateIndexFinder');
+const cb = require('./cb');
+const getLength = require('./getLength');
+
+
+// Generator function to create the findIndex and findLastIndex functions
+var createPredicateIndexFinder = function(dir) {
+    return function(array, predicate, context) {
+        predicate = cb(predicate, context);
+        var length = getLength(array);
+        var index = dir > 0 ? 0 : length - 1;
+        for (; index >= 0 && index < length; index += dir) {
+            if (predicate(array[index], index, array)) return index;
+        }
+        return -1;
+    };
+};
 
 // Returns the first index on an array-like that passes a predicate test.
 module.exports = createPredicateIndexFinder(1);
\ No newline at end of file
diff --git a/first.js b/first.js
index c11dff916..1846cfd6c 100644
--- a/first.js
+++ b/first.js
@@ -5,15 +5,15 @@ module.exports = function first(array, n, guard) {
         n = 1;
     }
     var result = [];
-    find(array, function(value) {
+    find(array, function (value) {
         if (result.length !== n && result.length < n) {
             result.push(value);
         } else {
             return true;
         }
     });
-    if (result.length === 1) {
+    if (result.length && n === 1) {
         result = result.pop();
     }
     return result;
-};
\ No newline at end of file
+};
diff --git a/getLength.js b/getLength.js
new file mode 100644
index 000000000..cde55a731
--- /dev/null
+++ b/getLength.js
@@ -0,0 +1 @@
+module.exports = require('./property')('length');
\ No newline at end of file
diff --git a/id.js b/id.js
new file mode 100644
index 000000000..f190d7c6c
--- /dev/null
+++ b/id.js
@@ -0,0 +1,3 @@
+module.exports = function (id) {
+    return id;
+}
\ No newline at end of file
diff --git a/includes.js b/includes.js
new file mode 100644
index 000000000..fc94d2905
--- /dev/null
+++ b/includes.js
@@ -0,0 +1,10 @@
+// Determine if the array or object contains a given item (using `===`).
+// Aliased as `includes` and `include`.
+const isArrayLike = require('./isArrayLike');
+const indexOf = require('./indexOf');
+
+module.exports = function(obj, item, fromIndex, guard) {
+    if (!isArrayLike(obj)) obj = require('./values')(obj);
+    if (typeof fromIndex != 'number' || guard) fromIndex = 0;
+    return indexOf(obj, item, fromIndex) >= 0;
+};
\ No newline at end of file
diff --git a/indexOf.js b/indexOf.js
index 9a4ac5dbb..a17f82b80 100644
--- a/indexOf.js
+++ b/indexOf.js
@@ -1,9 +1,68 @@
-const createIndexFinder = require('./_createIndexFinder');
-const findIndex = require('./findIndex');
-const sortedIndex = require('./sortedIndex');
+const getLength = require('./getLength');
+const cb = require('./cb');
+const isNumber = require('./isNumber');
+
+const _isNaN = function(obj) {
+    return _.isNumber(obj) && isNaN(obj);
+};
+
+// Generator function to create the findIndex and findLastIndex functions
+var createPredicateIndexFinder = function(dir) {
+    return function(array, predicate, context) {
+        predicate = cb(predicate, context);
+        var length = getLength(array);
+        var index = dir > 0 ? 0 : length - 1;
+        for (; index >= 0 && index < length; index += dir) {
+            if (predicate(array[index], index, array)) return index;
+        }
+        return -1;
+    };
+};
+
+  // Returns the first index on an array-like that passes a predicate test
+const findIndex = createPredicateIndexFinder(1);
+ 
+
+  // Use a comparator function to figure out the smallest index at which
+  // an object should be inserted so as to maintain order. Uses binary search.
+const sortedIndex = function(array, obj, iteratee, context) {
+    iteratee = cb(iteratee, context, 1);
+    var value = iteratee(obj);
+    var low = 0, high = getLength(array);
+    while (low < high) {
+       var mid = Math.floor((low + high) / 2);
+       if (iteratee(array[mid]) < value) low = mid + 1; else high = mid;
+    }
+    return low;
+};
+
+  // Generator function to create the indexOf and lastIndexOf functions
+var createIndexFinder = function(dir, predicateFind, sortedIndex) {
+    return function(array, item, idx) {
+        var i = 0, length = getLength(array);
+        if (typeof idx == 'number') {
+            if (dir > 0) {
+                i = idx >= 0 ? idx : Math.max(idx + length, i);
+            } else {
+                length = idx >= 0 ? Math.min(idx + 1, length) : idx + length + 1;
+            }
+        } else if (sortedIndex && idx && length) {
+            idx = sortedIndex(array, item);
+            return array[idx] === item ? idx : -1;
+        }
+        if (item !== item) {
+            idx = predicateFind(slice.call(array, i, length), _isNaN);
+            return idx >= 0 ? idx + i : -1;
+        }
+        for (idx = dir > 0 ? i : length - 1; idx >= 0 && idx < length; idx += dir) {
+            if (array[idx] === item) return idx;
+        }
+        return -1;
+    };
+};
 
 // Return the position of the first occurrence of an item in an array,
 // or -1 if the item is not included in the array.
 // If the array is large and already in sort order, pass `true`
 // for **isSorted** to use binary search.
-module.exports = createIndexFinder(1, findIndex, sortedIndex);
\ No newline at end of file
+  module.exports = createIndexFinder(1, findIndex, sortedIndex);
\ No newline at end of file
diff --git a/isArrayLike.js b/isArrayLike.js
new file mode 100644
index 000000000..c3c48bf25
--- /dev/null
+++ b/isArrayLike.js
@@ -0,0 +1,7 @@
+const getLength = require('./getLength');
+const MAX_ARRAY_INDEX = Math.pow(2, 53) - 1;
+
+module.exports = function(collection) {
+    const length = getLength(collection);
+    return typeof length == 'number' && length >= 0 && length <= MAX_ARRAY_INDEX;
+};
\ No newline at end of file
diff --git a/isBoolean.js b/isBoolean.js
index 4287e8f6e..d0a1faf66 100644
--- a/isBoolean.js
+++ b/isBoolean.js
@@ -1,4 +1,3 @@
-// Is a given value a boolean?
 module.exports = function(obj) {
-  return obj === true || obj === false || Object.prototype.toString.call(obj) === '[object Boolean]';
+    return obj === true || obj === false || Object.prototype.toString.call(obj) === '[object Boolean]';
 };
\ No newline at end of file
diff --git a/isNumber.js b/isNumber.js
new file mode 100644
index 000000000..188b9aec1
--- /dev/null
+++ b/isNumber.js
@@ -0,0 +1,3 @@
+module.exports = function(obj) {
+    return Object.prototype.toString.call(obj) === '[object Number]';
+};
\ No newline at end of file
diff --git a/range.js b/range.js
index 89f3ff55f..60490e8eb 100644
--- a/range.js
+++ b/range.js
@@ -1,4 +1,4 @@
-module.exports = function range(start, stop, step) {
+module.exports = function(start, stop, step) {
     if (stop == null) {
         stop = start || 0;
         start = 0;
@@ -8,11 +8,11 @@ module.exports = function range(start, stop, step) {
     }
 
     var length = Math.max(Math.ceil((stop - start) / step), 0);
-    var rng = new Array(length);
+    var range = Array(length);
 
     for (var idx = 0; idx < length; idx++, start += step) {
-        rng[idx] = start;
+        range[idx] = start;
     }
 
-    return rng;
+    return range;
 };
\ No newline at end of file
diff --git a/sortedIndex.js b/sortedIndex.js
index 1e37f4207..ae7b69c26 100644
--- a/sortedIndex.js
+++ b/sortedIndex.js
@@ -1,5 +1,5 @@
 const cb = require('./cb');
-const getLength = require('./_arrayHelper').getLength;
+const getLength = require('./getLength');
 
 // Use a comparator function to figure out the smallest index at which
 // an object should be inserted so as to maintain order. Uses binary search.
diff --git a/underscore.js b/underscore.js
index 25ba35037..5318d1009 100644
--- a/underscore.js
+++ b/underscore.js
@@ -382,26 +382,7 @@
   };
 
   // Return the maximum element (or element-based computation).
-  _.max = function(obj, iteratee, context) {
-    var result = -Infinity, lastComputed = -Infinity, computed;
-    if (iteratee == null || (typeof iteratee == 'number' && typeof obj[0] != 'object') && obj != null) {
-      _.each(obj, function(value) {
-        if (value > result) {
-          result = value;
-        }
-      });
-    } else {
-      iteratee = cb(iteratee, context);
-      _.each(obj, function(v, index, list) {
-        computed = iteratee(v, index, list);
-        if (computed > lastComputed || computed === -Infinity && result === -Infinity) {
-          result = v;
-          lastComputed = computed;
-        }
-      });
-    }
-    return result;
-  };
+  _.max = require('./max');
 
   // Return the minimum element (or element-based computation).
   _.min = function(obj, iteratee, context) {
@@ -504,16 +485,16 @@
   _.countBy = group(function(result, value, key) {
     if (_.has(result, key)) result[key]++; else result[key] = 1;
   });
-  
+
   var reStrSymbol = /[^\ud800-\udfff]|[\ud800-\udbff][\udc00-\udfff]|[\ud800-\udfff]/g;
   // Safely create a real, live array from anything iterable.
   _.toArray = function(obj) {
     if (!obj) return [];
     if (_.isArray(obj)) return slice.call(obj);
     if (_.isString(obj)) {
-        // Keep surrogate pair characters together
-        return obj.match(reStrSymbol);
-      }
+      // Keep surrogate pair characters together
+      return obj.match(reStrSymbol);
+    }
     if (isArrayLike(obj)) return _.map(obj, _.identity);
     return _.values(obj);
   };
@@ -549,7 +530,7 @@
         return true;
       }
     });
-    if (result.length === 1) {
+    if (result.length && n === 1) {
       result = result.pop();
     }
     return result;
@@ -783,24 +764,7 @@
   // Generate an integer Array containing an arithmetic progression. A port of
   // the native Python `range()` function. See
   // [the Python documentation](http://docs.python.org/library/functions.html#range).
-  _.range = function(start, stop, step) {
-    if (stop == null) {
-      stop = start || 0;
-      start = 0;
-    }
-    if (!step) {
-      step = stop < start ? -1 : 1;
-    }
-
-    var length = Math.max(Math.ceil((stop - start) / step), 0);
-    var range = Array(length);
-
-    for (var idx = 0; idx < length; idx++, start += step) {
-      range[idx] = start;
-    }
-
-    return range;
-  };
+  _.range = require('./range');
 
   // Split an **array** into several arrays containing **count** or less elements
   // of initial array
@@ -1357,7 +1321,6 @@
   }
 
 
-
   // Is a given object a finite number?
   _.isFinite = function(obj) {
     return !_.isSymbol(obj) && isFinite(obj) && !isNaN(parseFloat(obj));
@@ -1655,4 +1618,4 @@
     return '' + this._wrapped;
   };
 
-}(this));
+}(module.exports));
diff --git a/uniq.js b/uniq.js
index 47aeab5bd..c239ec584 100644
--- a/uniq.js
+++ b/uniq.js
@@ -1,35 +1,33 @@
-const restArgs = require('./restArgs');
-const isBoolean = require('./isBoolean');
-const getLength = require('./_arrayHelper').getLength;
-const cb = require('./cb');
-const contains = require('./contains');
-
 // Produce a duplicate-free version of the array. If the array has already
 // been sorted, you have the option of using a faster algorithm.
-// Aliased as `unique`.
-module.exports =  function(array, isSorted, iteratee, context) {
+const getLength = require('./getLength');
+const contains = require('./includes');
+const cb = require('./cb');
+const isBoolean = require('./isBoolean');
+
+module.exports = function(array, isSorted, iteratee, context) {
     if (!isBoolean(isSorted)) {
-      context = iteratee;
-      iteratee = isSorted;
-      isSorted = false;
+        context = iteratee;
+        iteratee = isSorted;
+        isSorted = false;
     }
     if (iteratee != null) iteratee = cb(iteratee, context);
     var result = [];
     var seen = [];
     for (var i = 0, length = getLength(array); i < length; i++) {
-      var value = array[i],
-          computed = iteratee ? iteratee(value, i, array) : value;
-      if (isSorted) {
+        var value = array[i],
+            computed = iteratee ? iteratee(value, i, array) : value;
+        if (isSorted) {
         if (!i || seen !== computed) result.push(value);
         seen = computed;
-      } else if (iteratee) {
+        } else if (iteratee) {
         if (!contains(seen, computed)) {
-          seen.push(computed);
-          result.push(value);
+            seen.push(computed);
+            result.push(value);
         }
-      } else if (!contains(result, value)) {
+        } else if (!contains(result, value)) {
         result.push(value);
-      }
+        }
     }
     return result;
 };
\ No newline at end of file