tweet_live: comparison web/res/js/underscore.js

Mercurial Mercurial > tweet_live / comparison

summary | shortlog | changelog | graph | tags | bookmarks | branches | files | changeset | file | latest | revisions | annotate | diff | comparison | raw | help

web/res/js/underscore.js

changeset 1304	10974bff4dae
parent 1198	ff4b567d51f2
child 1514	5869151a1f2f

equal deleted inserted replaced

-:20e00017dd60
+:10974bff4dae
-//     Underscore.js 1.5.2
+//     Underscore.js 1.8.3
 //     http://underscorejs.org
-//     (c) 2009-2013 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
+//     (c) 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 //     Underscore may be freely distributed under the MIT license.
 (function() {
 // Baseline setup
 // Establish the root object, `window` in the browser, or `exports` on the server.
 var root = this;
 // Save the previous value of the `_` variable.
 var previousUnderscore = root._;
-// Establish the object that gets returned to break out of a loop iteration.
-var breaker = {};
 // Save bytes in the minified (but not gzipped) version:
 var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;
 // Create quick reference variables for speed access to core prototypes.
 var
 push             = ArrayProto.push,
 slice            = ArrayProto.slice,
-concat           = ArrayProto.concat,
 toString         = ObjProto.toString,
 hasOwnProperty   = ObjProto.hasOwnProperty;
 // All **ECMAScript 5** native function implementations that we hope to use
 // are declared here.
 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;
+nativeBind         = FuncProto.bind,
+nativeCreate       = Object.create;
+// Naked function reference for surrogate-prototype-swapping.
+var Ctor = function(){};
 // Create a safe reference to the Underscore object for use below.
 var _ = function(obj) {
 if (obj instanceof _) return obj;
 if (!(this instanceof _)) return new _(obj);
 this._wrapped = obj;
 };
 // Export the Underscore object for **Node.js**, with
 // backwards-compatibility for the old `require()` API. If we're in
-// the browser, add `_` as a global object via a string identifier,
+// the browser, add `_` as a global object.
-// for Closure Compiler "advanced" mode.
 if (typeof exports !== 'undefined') {
 if (typeof module !== 'undefined' && module.exports) {
 exports = module.exports = _;
 }
 exports._ = _;
 } else {
 root._ = _;
 }
 // Current version.
-_.VERSION = '1.5.2';
+_.VERSION = '1.8.3';
+// Internal function that returns an efficient (for current engines) version
+// of the passed-in callback, to be repeatedly applied in other Underscore
+// functions.
+var optimizeCb = function(func, context, argCount) {
+if (context === void 0) return func;
+switch (argCount == null ? 3 : argCount) {
+case 1: return function(value) {
+return func.call(context, value);
+};
+case 2: return function(value, other) {
+return func.call(context, value, other);
+};
+case 3: return function(value, index, collection) {
+return func.call(context, value, index, collection);
+};
+case 4: return function(accumulator, value, index, collection) {
+return func.call(context, accumulator, value, index, collection);
+};
+}
+return function() {
+return func.apply(context, arguments);
+};
+};
+// A mostly-internal function to generate callbacks that can be applied
+// to each element in a collection, returning the desired result — either
+// identity, an arbitrary callback, a property matcher, or a property accessor.
+var cb = function(value, context, argCount) {
+if (value == null) return _.identity;
+if (_.isFunction(value)) return optimizeCb(value, context, argCount);
+if (_.isObject(value)) return _.matcher(value);
+return _.property(value);
+};
+_.iteratee = function(value, context) {
+return cb(value, context, Infinity);
+};
+// An internal function for creating assigner functions.
+var createAssigner = function(keysFunc, undefinedOnly) {
+return function(obj) {
+var length = arguments.length;
+if (length < 2 || obj == null) return obj;
+for (var index = 1; index < length; index++) {
+var source = arguments[index],
+keys = keysFunc(source),
+l = keys.length;
+for (var i = 0; i < l; i++) {
+var key = keys[i];
+if (!undefinedOnly || obj[key] === void 0) obj[key] = source[key];
+}
+}
+return obj;
+};
+};
+// An internal function for creating a new object that inherits from another.
+var baseCreate = function(prototype) {
+if (!_.isObject(prototype)) return {};
+if (nativeCreate) return nativeCreate(prototype);
+Ctor.prototype = prototype;
+var result = new Ctor;
+Ctor.prototype = null;
+return result;
+};
+var property = function(key) {
+return function(obj) {
+return obj == null ? void 0 : obj[key];
+};
+};
+// Helper for collection methods to determine whether a collection
+// 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
+var MAX_ARRAY_INDEX = Math.pow(2, 53) - 1;
+var getLength = property('length');
+var isArrayLike = function(collection) {
+var length = getLength(collection);
+return typeof length == 'number' && length >= 0 && length <= MAX_ARRAY_INDEX;
+};
 // Collection Functions
 // --------------------
 // The cornerstone, an `each` implementation, aka `forEach`.
-// Handles objects with the built-in `forEach`, arrays, and raw objects.
+// Handles raw objects in addition to array-likes. Treats all
-// Delegates to **ECMAScript 5**'s native `forEach` if available.
+// sparse array-likes as if they were dense.
-var each = _.each = _.forEach = function(obj, iterator, context) {
+_.each = _.forEach = function(obj, iteratee, context) {
-if (obj == null) return;
+iteratee = optimizeCb(iteratee, context);
-if (nativeForEach && obj.forEach === nativeForEach) {
+var i, length;
-obj.forEach(iterator, context);
+if (isArrayLike(obj)) {
-} else if (obj.length === +obj.length) {
+for (i = 0, length = obj.length; i < length; i++) {
-for (var i = 0, length = obj.length; i < length; i++) {
+iteratee(obj[i], i, obj);
-if (iterator.call(context, obj[i], i, obj) === breaker) return;
 }
 } else {
 var keys = _.keys(obj);
-for (var i = 0, length = keys.length; i < length; i++) {
+for (i = 0, length = keys.length; i < length; i++) {
-if (iterator.call(context, obj[keys[i]], keys[i], obj) === breaker) return;
+iteratee(obj[keys[i]], keys[i], obj);
 }
 }
-};
+return obj;
+};
-// Return the results of applying the iterator to each element.
-// Delegates to **ECMAScript 5**'s native `map` if available.
+// Return the results of applying the iteratee to each element.
-_.map = _.collect = function(obj, iterator, context) {
+_.map = _.collect = function(obj, iteratee, context) {
+iteratee = cb(iteratee, context);
+var keys = !isArrayLike(obj) && _.keys(obj),
+length = (keys || obj).length,
+results = Array(length);
+for (var index = 0; index < length; index++) {
+var currentKey = keys ? keys[index] : index;
+results[index] = iteratee(obj[currentKey], currentKey, obj);
+}
+return results;
+};
+// Create a reducing function iterating left or right.
+function createReduce(dir) {
+// Optimized iterator function as using arguments.length
+// in the main function will deoptimize the, see #1991.
+function iterator(obj, iteratee, memo, keys, index, length) {
+for (; index >= 0 && index < length; index += dir) {
+var currentKey = keys ? keys[index] : index;
+memo = iteratee(memo, obj[currentKey], currentKey, obj);
+}
+return memo;
+}
+return function(obj, iteratee, memo, context) {
+iteratee = optimizeCb(iteratee, context, 4);
+var keys = !isArrayLike(obj) && _.keys(obj),
+length = (keys || obj).length,
+index = dir > 0 ? 0 : length - 1;
+// Determine the initial value if none is provided.
+if (arguments.length < 3) {
+memo = obj[keys ? keys[index] : index];
+index += dir;
+}
+return iterator(obj, iteratee, memo, keys, index, length);
+};
+}
+// **Reduce** builds up a single result from a list of values, aka `inject`,
+// or `foldl`.
+_.reduce = _.foldl = _.inject = createReduce(1);
+// The right-associative version of reduce, also known as `foldr`.
+_.reduceRight = _.foldr = createReduce(-1);
+// Return the first value which passes a truth test. Aliased as `detect`.
+_.find = _.detect = function(obj, predicate, context) {
+var key;
+if (isArrayLike(obj)) {
+key = _.findIndex(obj, predicate, context);
+} else {
+key = _.findKey(obj, predicate, context);
+}
+if (key !== void 0 && key !== -1) return obj[key];
+};
+// Return all the elements that pass a truth test.
+// Aliased as `select`.
+_.filter = _.select = function(obj, predicate, context) {
 var results = [];
-if (obj == null) return results;
+predicate = cb(predicate, context);
-if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
+_.each(obj, function(value, index, list) {
-each(obj, function(value, index, list) {
+if (predicate(value, index, list)) results.push(value);
-results.push(iterator.call(context, value, index, list));
 });
 return results;
 };
-var reduceError = 'Reduce of empty array with no initial value';
-// **Reduce** builds up a single result from a list of values, aka `inject`,
-// or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
-_.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
-var initial = arguments.length > 2;
-if (obj == null) obj = [];
-if (nativeReduce && obj.reduce === nativeReduce) {
-if (context) iterator = _.bind(iterator, context);
-return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
-}
-each(obj, function(value, index, list) {
-if (!initial) {
-memo = value;
-initial = true;
-} else {
-memo = iterator.call(context, memo, value, index, list);
-}
-});
-if (!initial) throw new TypeError(reduceError);
-return memo;
-};
-// The right-associative version of reduce, also known as `foldr`.
-// Delegates to **ECMAScript 5**'s native `reduceRight` if available.
-_.reduceRight = _.foldr = function(obj, iterator, memo, context) {
-var initial = arguments.length > 2;
-if (obj == null) obj = [];
-if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
-if (context) iterator = _.bind(iterator, context);
-return initial ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
-}
-var length = obj.length;
-if (length !== +length) {
-var keys = _.keys(obj);
-length = keys.length;
-}
-each(obj, function(value, index, list) {
-index = keys ? keys[--length] : --length;
-if (!initial) {
-memo = obj[index];
-initial = true;
-} else {
-memo = iterator.call(context, memo, obj[index], index, list);
-}
-});
-if (!initial) throw new TypeError(reduceError);
-return memo;
-};
-// Return the first value which passes a truth test. Aliased as `detect`.
-_.find = _.detect = 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;
-};
-// Return all the elements that pass a truth test.
-// Delegates to **ECMAScript 5**'s native `filter` if available.
-// Aliased as `select`.
-_.filter = _.select = function(obj, iterator, context) {
-var results = [];
-if (obj == null) return results;
-if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
-each(obj, function(value, index, list) {
-if (iterator.call(context, value, index, list)) results.push(value);
-});
-return results;
-};
 // Return all the elements for which a truth test fails.
-_.reject = function(obj, iterator, context) {
+_.reject = function(obj, predicate, context) {
-return _.filter(obj, function(value, index, list) {
+return _.filter(obj, _.negate(cb(predicate)), context);
-return !iterator.call(context, value, index, list);
-}, context);
 };
 // Determine whether all of the elements match a truth test.
-// Delegates to **ECMAScript 5**'s native `every` if available.
 // Aliased as `all`.
-_.every = _.all = function(obj, iterator, context) {
+_.every = _.all = function(obj, predicate, context) {
-iterator || (iterator = _.identity);
+predicate = cb(predicate, context);
-var result = true;
+var keys = !isArrayLike(obj) && _.keys(obj),
-if (obj == null) return result;
+length = (keys || obj).length;
-if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
+for (var index = 0; index < length; index++) {
-each(obj, function(value, index, list) {
+var currentKey = keys ? keys[index] : index;
-if (!(result = result && iterator.call(context, value, index, list))) return breaker;
+if (!predicate(obj[currentKey], currentKey, obj)) return false;
-});
+}
-return !!result;
+return true;
 };
 // 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 = _.some = _.any = function(obj, iterator, context) {
+_.some = _.any = function(obj, predicate, context) {
-iterator || (iterator = _.identity);
+predicate = cb(predicate, context);
-var result = false;
+var keys = !isArrayLike(obj) && _.keys(obj),
-if (obj == null) return result;
+length = (keys || obj).length;
-if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
+for (var index = 0; index < length; index++) {
-each(obj, function(value, index, list) {
+var currentKey = keys ? keys[index] : index;
-if (result || (result = iterator.call(context, value, index, list))) return breaker;
+if (predicate(obj[currentKey], currentKey, obj)) return true;
-});
+}
-return !!result;
+return false;
 };
-// Determine if the array or object contains a given value (using `===`).
+// Determine if the array or object contains a given item (using `===`).
-// Aliased as `include`.
+// Aliased as `includes` and `include`.
-_.contains = _.include = function(obj, target) {
+_.contains = _.includes = _.include = function(obj, item, fromIndex, guard) {
-if (obj == null) return false;
+if (!isArrayLike(obj)) obj = _.values(obj);
-if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
+if (typeof fromIndex != 'number' || guard) fromIndex = 0;
-return any(obj, function(value) {
+return _.indexOf(obj, item, fromIndex) >= 0;
-return value === target;
-});
 };
 // Invoke a method (with arguments) on every item in a collection.
 _.invoke = function(obj, method) {
 var args = slice.call(arguments, 2);
 var isFunc = _.isFunction(method);
 return _.map(obj, function(value) {
-return (isFunc ? method : value[method]).apply(value, args);
+var func = isFunc ? method : value[method];
+return func == null ? func : func.apply(value, args);
 });
 };
 // Convenience version of a common use case of `map`: fetching a property.
 _.pluck = function(obj, key) {
-return _.map(obj, function(value){ return value[key]; });
+return _.map(obj, _.property(key));
 };
 // Convenience version of a common use case of `filter`: selecting only objects
 // containing specific `key:value` pairs.
-_.where = function(obj, attrs, first) {
+_.where = function(obj, attrs) {
-if (_.isEmpty(attrs)) return first ? void 0 : [];
+return _.filter(obj, _.matcher(attrs));
-return _[first ? 'find' : 'filter'](obj, function(value) {
-for (var key in attrs) {
-if (attrs[key] !== value[key]) return false;
-}
-return true;
-});
 };
 // Convenience version of a common use case of `find`: getting the first object
 // containing specific `key:value` pairs.
 _.findWhere = function(obj, attrs) {
-return _.where(obj, attrs, true);
+return _.find(obj, _.matcher(attrs));
 };
-// Return the maximum element or (element-based computation).
+// Return the maximum element (or element-based computation).
-// Can't optimize arrays of integers longer than 65,535 elements.
+_.max = function(obj, iteratee, context) {
-// See [WebKit Bug 80797](https://bugs.webkit.org/show_bug.cgi?id=80797)
+var result = -Infinity, lastComputed = -Infinity,
-_.max = function(obj, iterator, context) {
+value, computed;
-if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
+if (iteratee == null && obj != null) {
-return Math.max.apply(Math, obj);
+obj = isArrayLike(obj) ? obj : _.values(obj);
-}
+for (var i = 0, length = obj.length; i < length; i++) {
-if (!iterator && _.isEmpty(obj)) return -Infinity;
+value = obj[i];
-var result = {computed : -Infinity, value: -Infinity};
+if (value > result) {
-each(obj, function(value, index, list) {
+result = value;
-var computed = iterator ? iterator.call(context, value, index, list) : value;
+}
-computed > result.computed && (result = {value : value, computed : computed});
+}
-});
+} else {
-return result.value;
+iteratee = cb(iteratee, context);
+_.each(obj, function(value, index, list) {
+computed = iteratee(value, index, list);
+if (computed > lastComputed || computed === -Infinity && result === -Infinity) {
+result = value;
+lastComputed = computed;
+}
+});
+}
+return result;
 };
 // Return the minimum element (or element-based computation).
-_.min = function(obj, iterator, context) {
+_.min = function(obj, iteratee, context) {
-if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
+var result = Infinity, lastComputed = Infinity,
-return Math.min.apply(Math, obj);
+value, computed;
-}
+if (iteratee == null && obj != null) {
-if (!iterator && _.isEmpty(obj)) return Infinity;
+obj = isArrayLike(obj) ? obj : _.values(obj);
-var result = {computed : Infinity, value: Infinity};
+for (var i = 0, length = obj.length; i < length; i++) {
-each(obj, function(value, index, list) {
+value = obj[i];
-var computed = iterator ? iterator.call(context, value, index, list) : value;
+if (value < result) {
-computed < result.computed && (result = {value : value, computed : computed});
+result = value;
-});
+}
-return result.value;
+}
-};
+} else {
+iteratee = cb(iteratee, context);
-// Shuffle an array, using the modern version of the
+_.each(obj, function(value, index, list) {
+computed = iteratee(value, index, list);
+if (computed < lastComputed || computed === Infinity && result === Infinity) {
+result = value;
+lastComputed = computed;
+}
+});
+}
+return result;
+};
+// Shuffle a collection, using the modern version of the
 // [Fisher-Yates shuffle](http://en.wikipedia.org/wiki/Fisher–Yates_shuffle).
 _.shuffle = function(obj) {
-var rand;
+var set = isArrayLike(obj) ? obj : _.values(obj);
-var index = 0;
+var length = set.length;
-var shuffled = [];
+var shuffled = Array(length);
-each(obj, function(value) {
+for (var index = 0, rand; index < length; index++) {
-rand = _.random(index++);
+rand = _.random(0, index);
-shuffled[index - 1] = shuffled[rand];
+if (rand !== index) shuffled[index] = shuffled[rand];
-shuffled[rand] = value;
+shuffled[rand] = set[index];
-});
+}
 return shuffled;
 };
-// Sample **n** random values from an array.
+// Sample **n** random values from a collection.
-// If **n** is not specified, returns a single random element from the array.
+// If **n** is not specified, returns a single random element.
 // The internal `guard` argument allows it to work with `map`.
 _.sample = function(obj, n, guard) {
-if (arguments.length < 2 || guard) {
+if (n == null || guard) {
+if (!isArrayLike(obj)) obj = _.values(obj);
 return obj[_.random(obj.length - 1)];
 }
 return _.shuffle(obj).slice(0, Math.max(0, n));
 };
-// An internal function to generate lookup iterators.
+// Sort the object's values by a criterion produced by an iteratee.
-var lookupIterator = function(value) {
+_.sortBy = function(obj, iteratee, context) {
-return _.isFunction(value) ? value : function(obj){ return obj[value]; };
+iteratee = cb(iteratee, context);
-};
-// Sort the object's values by a criterion produced by an iterator.
-_.sortBy = function(obj, value, context) {
-var iterator = lookupIterator(value);
 return _.pluck(_.map(obj, function(value, index, list) {
 return {
 value: value,
 index: index,
-criteria: iterator.call(context, value, index, list)
+criteria: iteratee(value, index, list)
 };
 }).sort(function(left, right) {
 var a = left.criteria;
 var b = right.criteria;
 if (a !== b) {
 }), 'value');
 };
 // An internal function used for aggregate "group by" operations.
 var group = function(behavior) {
-return function(obj, value, context) {
+return function(obj, iteratee, context) {
 var result = {};
-var iterator = value == null ? _.identity : lookupIterator(value);
+iteratee = cb(iteratee, context);
-each(obj, function(value, index) {
+_.each(obj, function(value, index) {
-var key = iterator.call(context, value, index, obj);
+var key = iteratee(value, index, obj);
-behavior(result, key, value);
+behavior(result, value, key);
 });
 return result;
 };
 };
 // Groups the object's values by a criterion. Pass either a string attribute
 // to group by, or a function that returns the criterion.
-_.groupBy = group(function(result, key, value) {
+_.groupBy = group(function(result, value, key) {
-(_.has(result, key) ? result[key] : (result[key] = [])).push(value);
+if (_.has(result, key)) result[key].push(value); else result[key] = [value];
 });
 // Indexes the object's values by a criterion, similar to `groupBy`, but for
 // when you know that your index values will be unique.
-_.indexBy = group(function(result, key, value) {
+_.indexBy = group(function(result, value, key) {
 result[key] = value;
 });
 // Counts instances of an object that group by a certain criterion. Pass
 // either a string attribute to count by, or a function that returns the
 // criterion.
-_.countBy = group(function(result, key) {
+_.countBy = group(function(result, value, key) {
-_.has(result, key) ? result[key]++ : result[key] = 1;
+if (_.has(result, key)) result[key]++; else result[key] = 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.
-_.sortedIndex = function(array, obj, iterator, context) {
-iterator = iterator == null ? _.identity : lookupIterator(iterator);
-var value = iterator.call(context, obj);
-var low = 0, high = array.length;
-while (low < high) {
-var mid = (low + high) >>> 1;
-iterator.call(context, array[mid]) < value ? low = mid + 1 : high = mid;
-}
-return low;
-};
 // Safely create a real, live array from anything iterable.
 _.toArray = function(obj) {
 if (!obj) return [];
 if (_.isArray(obj)) return slice.call(obj);
-if (obj.length === +obj.length) return _.map(obj, _.identity);
+if (isArrayLike(obj)) return _.map(obj, _.identity);
 return _.values(obj);
 };
 // Return the number of elements in an object.
 _.size = function(obj) {
 if (obj == null) return 0;
-return (obj.length === +obj.length) ? obj.length : _.keys(obj).length;
+return isArrayLike(obj) ? obj.length : _.keys(obj).length;
+};
+// Split a collection into two arrays: one whose elements all satisfy the given
+// predicate, and one whose elements all do not satisfy the predicate.
+_.partition = function(obj, predicate, context) {
+predicate = cb(predicate, context);
+var pass = [], fail = [];
+_.each(obj, function(value, key, obj) {
+(predicate(value, key, obj) ? pass : fail).push(value);
+});
+return [pass, fail];
 };
 // Array Functions
 // ---------------
 // Get the first element of an array. Passing **n** will return the first N
 // values in the array. Aliased as `head` and `take`. The **guard** check
 // allows it to work with `_.map`.
 _.first = _.head = _.take = function(array, n, guard) {
 if (array == null) return void 0;
-return (n == null) || guard ? array[0] : slice.call(array, 0, n);
+if (n == null || guard) return array[0];
+return _.initial(array, array.length - n);
 };
 // Returns everything but the last entry of the array. Especially useful on
 // the arguments object. Passing **n** will return all the values in
-// the array, excluding the last N. The **guard** check allows it to work with
+// the array, excluding the last N.
-// `_.map`.
 _.initial = function(array, n, guard) {
-return slice.call(array, 0, array.length - ((n == null) || guard ? 1 : n));
+return slice.call(array, 0, Math.max(0, array.length - (n == null || guard ? 1 : n)));
 };
 // Get the last element of an array. Passing **n** will return the last N
-// values in the array. The **guard** check allows it to work with `_.map`.
+// values in the array.
 _.last = function(array, n, guard) {
 if (array == null) return void 0;
-if ((n == null) || guard) {
+if (n == null || guard) return array[array.length - 1];
-return array[array.length - 1];
+return _.rest(array, Math.max(0, array.length - n));
-} else {
-return slice.call(array, Math.max(array.length - n, 0));
-}
 };
 // Returns everything but the first entry of the array. Aliased as `tail` and `drop`.
 // Especially useful on the arguments object. Passing an **n** will return
-// the rest N values in the array. The **guard**
+// the rest N values in the array.
-// check allows it to work with `_.map`.
 _.rest = _.tail = _.drop = function(array, n, guard) {
-return slice.call(array, (n == null) || guard ? 1 : n);
+return slice.call(array, n == null || guard ? 1 : n);
 };
 // Trim out all falsy values from an array.
 _.compact = function(array) {
 return _.filter(array, _.identity);
 };
 // Internal implementation of a recursive `flatten` function.
-var flatten = function(input, shallow, output) {
+var flatten = function(input, shallow, strict, startIndex) {
-if (shallow && _.every(input, _.isArray)) {
+var output = [], idx = 0;
-return concat.apply(output, input);
+for (var i = startIndex || 0, length = getLength(input); i < length; i++) {
-}
+var value = input[i];
-each(input, function(value) {
+if (isArrayLike(value) && (_.isArray(value) || _.isArguments(value))) {
-if (_.isArray(value) || _.isArguments(value)) {
+//flatten current level of array or arguments object
-shallow ? push.apply(output, value) : flatten(value, shallow, output);
+if (!shallow) value = flatten(value, shallow, strict);
-} else {
+var j = 0, len = value.length;
-output.push(value);
+output.length += len;
-}
+while (j < len) {
-});
+output[idx++] = value[j++];
+}
+} else if (!strict) {
+output[idx++] = value;
+}
+}
 return output;
 };
 // Flatten out an array, either recursively (by default), or just one level.
 _.flatten = function(array, shallow) {
-return flatten(array, shallow, []);
+return flatten(array, shallow, false);
 };
 // Return a version of the array that does not contain the specified value(s).
 _.without = function(array) {
 return _.difference(array, slice.call(arguments, 1));
 };
 // 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`.
-_.uniq = _.unique = function(array, isSorted, iterator, context) {
+_.uniq = _.unique = function(array, isSorted, iteratee, context) {
-if (_.isFunction(isSorted)) {
+if (!_.isBoolean(isSorted)) {
-context = iterator;
+context = iteratee;
-iterator = isSorted;
+iteratee = isSorted;
 isSorted = false;
 }
-var initial = iterator ? _.map(array, iterator, context) : array;
+if (iteratee != null) iteratee = cb(iteratee, context);
-var results = [];
+var result = [];
 var seen = [];
-each(initial, function(value, index) {
+for (var i = 0, length = getLength(array); i < length; i++) {
-if (isSorted ? (!index || seen[seen.length - 1] !== value) : !_.contains(seen, value)) {
+var value = array[i],
-seen.push(value);
+computed = iteratee ? iteratee(value, i, array) : value;
-results.push(array[index]);
+if (isSorted) {
-}
+if (!i || seen !== computed) result.push(value);
-});
+seen = computed;
-return results;
+} else if (iteratee) {
+if (!_.contains(seen, computed)) {
+seen.push(computed);
+result.push(value);
+}
+} else if (!_.contains(result, value)) {
+result.push(value);
+}
+}
+return result;
 };
 // Produce an array that contains the union: each distinct element from all of
 // the passed-in arrays.
 _.union = function() {
-return _.uniq(_.flatten(arguments, true));
+return _.uniq(flatten(arguments, true, true));
 };
 // Produce an array that contains every item shared between all the
 // passed-in arrays.
 _.intersection = function(array) {
-var rest = slice.call(arguments, 1);
+var result = [];
-return _.filter(_.uniq(array), function(item) {
+var argsLength = arguments.length;
-return _.every(rest, function(other) {
+for (var i = 0, length = getLength(array); i < length; i++) {
-return _.indexOf(other, item) >= 0;
+var item = array[i];
-});
+if (_.contains(result, item)) continue;
-});
+for (var j = 1; j < argsLength; j++) {
+if (!_.contains(arguments[j], item)) break;
+}
+if (j === argsLength) result.push(item);
+}
+return result;
 };
 // Take the difference between one array and a number of other arrays.
 // Only the elements present in just the first array will remain.
 _.difference = function(array) {
-var rest = concat.apply(ArrayProto, slice.call(arguments, 1));
+var rest = flatten(arguments, true, true, 1);
-return _.filter(array, function(value){ return !_.contains(rest, value); });
+return _.filter(array, function(value){
+return !_.contains(rest, value);
+});
 };
 // Zip together multiple lists into a single array -- elements that share
 // an index go together.
 _.zip = function() {
-var length = _.max(_.pluck(arguments, "length").concat(0));
+return _.unzip(arguments);
-var results = new Array(length);
+};
-for (var i = 0; i < length; i++) {
-results[i] = _.pluck(arguments, '' + i);
+// Complement of _.zip. Unzip accepts an array of arrays and groups
-}
+// each array's elements on shared indices
-return results;
+_.unzip = function(array) {
+var length = array && _.max(array, getLength).length || 0;
+var result = Array(length);
+for (var index = 0; index < length; index++) {
+result[index] = _.pluck(array, index);
+}
+return result;
 };
 // Converts lists into objects. Pass either a single array of `[key, value]`
 // pairs, or two parallel arrays of the same length -- one of keys, and one of
 // the corresponding values.
 _.object = function(list, values) {
-if (list == null) return {};
 var result = {};
-for (var i = 0, length = list.length; i < length; i++) {
+for (var i = 0, length = getLength(list); i < length; i++) {
 if (values) {
 result[list[i]] = values[i];
 } else {
 result[list[i][0]] = list[i][1];
 }
 }
 return result;
 };
-// If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
+// Generator function to create the findIndex and findLastIndex functions
-// we need this function. Return the position of the first occurrence of an
+function createPredicateIndexFinder(dir) {
-// item in an array, or -1 if the item is not included in the array.
+return function(array, predicate, context) {
-// Delegates to **ECMAScript 5**'s native `indexOf` if available.
+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
+_.findIndex = createPredicateIndexFinder(1);
+_.findLastIndex = 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.
+_.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
+function createIndexFinder(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.
-_.indexOf = function(array, item, isSorted) {
+_.indexOf = createIndexFinder(1, _.findIndex, _.sortedIndex);
-if (array == null) return -1;
+_.lastIndexOf = createIndexFinder(-1, _.findLastIndex);
-var i = 0, length = array.length;
-if (isSorted) {
-if (typeof isSorted == 'number') {
-i = (isSorted < 0 ? Math.max(0, length + isSorted) : isSorted);
-} else {
-i = _.sortedIndex(array, item);
-return array[i] === item ? i : -1;
-}
-}
-if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
-for (; i < length; i++) if (array[i] === item) return i;
-return -1;
-};
-// Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
-_.lastIndexOf = function(array, item, from) {
-if (array == null) return -1;
-var hasIndex = from != null;
-if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) {
-return hasIndex ? array.lastIndexOf(item, from) : array.lastIndexOf(item);
-}
-var i = (hasIndex ? from : array.length);
-while (i--) if (array[i] === item) return i;
-return -1;
-};
 // 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 (arguments.length <= 1) {
+if (stop == null) {
 stop = start || 0;
 start = 0;
 }
-step = arguments[2] || 1;
+step = step || 1;
 var length = Math.max(Math.ceil((stop - start) / step), 0);
-var idx = 0;
+var range = Array(length);
-var range = new Array(length);
+for (var idx = 0; idx < length; idx++, start += step) {
-while(idx < length) {
+range[idx] = start;
-range[idx++] = start;
-start += step;
 }
 return range;
 };
 // Function (ahem) Functions
 // ------------------
-// Reusable constructor function for prototype setting.
+// Determines whether to execute a function as a constructor
-var ctor = function(){};
+// or a normal function with the provided arguments
+var executeBound = function(sourceFunc, boundFunc, context, callingContext, args) {
+if (!(callingContext instanceof boundFunc)) return sourceFunc.apply(context, args);
+var self = baseCreate(sourceFunc.prototype);
+var result = sourceFunc.apply(self, args);
+if (_.isObject(result)) return result;
+return self;
+};
 // Create a function bound to a given object (assigning `this`, and arguments,
 // optionally). Delegates to **ECMAScript 5**'s native `Function.bind` if
 // available.
 _.bind = function(func, context) {
-var args, bound;
 if (nativeBind && func.bind === nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
-if (!_.isFunction(func)) throw new TypeError;
+if (!_.isFunction(func)) throw new TypeError('Bind must be called on a function');
-args = slice.call(arguments, 2);
+var args = slice.call(arguments, 2);
-return bound = function() {
+var bound = function() {
-if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
+return executeBound(func, bound, context, this, args.concat(slice.call(arguments)));
-ctor.prototype = func.prototype;
+};
-var self = new ctor;
+return bound;
-ctor.prototype = null;
-var result = func.apply(self, args.concat(slice.call(arguments)));
-if (Object(result) === result) return result;
-return self;
-};
 };
 // Partially apply a function by creating a version that has had some of its
-// arguments pre-filled, without changing its dynamic `this` context.
+// arguments pre-filled, without changing its dynamic `this` context. _ acts
+// as a placeholder, allowing any combination of arguments to be pre-filled.
 _.partial = function(func) {
-var args = slice.call(arguments, 1);
+var boundArgs = slice.call(arguments, 1);
-return function() {
+var bound = function() {
-return func.apply(this, args.concat(slice.call(arguments)));
+var position = 0, length = boundArgs.length;
-};
+var args = Array(length);
-};
+for (var i = 0; i < length; i++) {
+args[i] = boundArgs[i] === _ ? arguments[position++] : boundArgs[i];
-// Bind all of an object's methods to that object. Useful for ensuring that
+}
-// all callbacks defined on an object belong to it.
+while (position < arguments.length) args.push(arguments[position++]);
+return executeBound(func, bound, this, this, args);
+};
+return bound;
+};
+// Bind a number of an object's methods to that object. Remaining arguments
+// are the method names to be bound. Useful for ensuring that all callbacks
+// defined on an object belong to it.
 _.bindAll = function(obj) {
-var funcs = slice.call(arguments, 1);
+var i, length = arguments.length, key;
-if (funcs.length === 0) throw new Error("bindAll must be passed function names");
+if (length <= 1) throw new Error('bindAll must be passed function names');
-each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
+for (i = 1; i < length; i++) {
+key = arguments[i];
+obj[key] = _.bind(obj[key], obj);
+}
 return obj;
 };
 // Memoize an expensive function by storing its results.
 _.memoize = function(func, hasher) {
-var memo = {};
+var memoize = function(key) {
-hasher || (hasher = _.identity);
+var cache = memoize.cache;
-return function() {
+var address = '' + (hasher ? hasher.apply(this, arguments) : key);
-var key = hasher.apply(this, arguments);
+if (!_.has(cache, address)) cache[address] = func.apply(this, arguments);
-return _.has(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
+return cache[address];
 };
+memoize.cache = {};
+return memoize;
 };
 // Delays a function for the given number of milliseconds, and then calls
 // it with the arguments supplied.
 _.delay = function(func, wait) {
 var args = slice.call(arguments, 2);
-return setTimeout(function(){ return func.apply(null, args); }, wait);
+return setTimeout(function(){
+return func.apply(null, args);
+}, wait);
 };
 // Defers a function, scheduling it to run after the current call stack has
 // cleared.
-_.defer = function(func) {
+_.defer = _.partial(_.delay, _, 1);
-return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
-};
 // Returns a function, that, when invoked, will only be triggered at most once
 // during a given window of time. Normally, the throttled function will run
 // as much as it can, without ever going more than once per `wait` duration;
 // but if you'd like to disable the execution on the leading edge, pass
 // `{leading: false}`. To disable execution on the trailing edge, ditto.
 _.throttle = function(func, wait, options) {
 var context, args, result;
 var timeout = null;
 var previous = 0;
-options || (options = {});
+if (!options) options = {};
 var later = function() {
-previous = options.leading === false ? 0 : new Date;
+previous = options.leading === false ? 0 : _.now();
 timeout = null;
 result = func.apply(context, args);
+if (!timeout) context = args = null;
 };
 return function() {
-var now = new Date;
+var now = _.now();
 if (!previous && options.leading === false) previous = now;
 var remaining = wait - (now - previous);
 context = this;
 args = arguments;
-if (remaining <= 0) {
+if (remaining <= 0 || remaining > wait) {
-clearTimeout(timeout);
+if (timeout) {
-timeout = null;
+clearTimeout(timeout);
+timeout = null;
+}
 previous = now;
 result = func.apply(context, args);
+if (!timeout) context = args = null;
 } else if (!timeout && options.trailing !== false) {
 timeout = setTimeout(later, remaining);
 }
 return result;
 };
 // be triggered. The function will be called after it stops being called for
 // N milliseconds. If `immediate` is passed, trigger the function on the
 // leading edge, instead of the trailing.
 _.debounce = function(func, wait, immediate) {
 var timeout, args, context, timestamp, result;
+var later = function() {
+var last = _.now() - timestamp;
+if (last < wait && last >= 0) {
+timeout = setTimeout(later, wait - last);
+} else {
+timeout = null;
+if (!immediate) {
+result = func.apply(context, args);
+if (!timeout) context = args = null;
+}
+}
+};
 return function() {
 context = this;
 args = arguments;
-timestamp = new Date();
+timestamp = _.now();
-var later = function() {
-var last = (new Date()) - timestamp;
-if (last < wait) {
-timeout = setTimeout(later, wait - last);
-} else {
-timeout = null;
-if (!immediate) result = func.apply(context, args);
-}
-};
 var callNow = immediate && !timeout;
-if (!timeout) {
+if (!timeout) timeout = setTimeout(later, wait);
-timeout = setTimeout(later, wait);
+if (callNow) {
-}
+result = func.apply(context, args);
-if (callNow) result = func.apply(context, args);
+context = args = null;
+}
 return result;
-};
-};
-// Returns a function that will be executed at most one time, no matter how
-// often you call it. Useful for lazy initialization.
-_.once = function(func) {
-var ran = false, memo;
-return function() {
-if (ran) return memo;
-ran = true;
-memo = func.apply(this, arguments);
-func = null;
-return memo;
 };
 };
 // Returns the first function passed as an argument to the second,
 // allowing you to adjust arguments, run code before and after, and
 // conditionally execute the original function.
 _.wrap = function(func, wrapper) {
+return _.partial(wrapper, func);
+};
+// Returns a negated version of the passed-in predicate.
+_.negate = function(predicate) {
 return function() {
-var args = [func];
+return !predicate.apply(this, arguments);
-push.apply(args, arguments);
-return wrapper.apply(this, args);
 };
 };
 // Returns a function that is the composition of a list of functions, each
 // consuming the return value of the function that follows.
 _.compose = function() {
-var funcs = arguments;
+var args = arguments;
+var start = args.length - 1;
 return function() {
-var args = arguments;
+var i = start;
-for (var i = funcs.length - 1; i >= 0; i--) {
+var result = args[start].apply(this, arguments);
-args = [funcs[i].apply(this, args)];
+while (i--) result = args[i].call(this, result);
-}
+return result;
-return args[0];
+};
 };
-};
+// Returns a function that will only be executed on and after the Nth call.
-// Returns a function that will only be executed after being called N times.
 _.after = function(times, func) {
 return function() {
 if (--times < 1) {
 return func.apply(this, arguments);
 }
 };
 };
+// Returns a function that will only be executed up to (but not including) the Nth call.
+_.before = function(times, func) {
+var memo;
+return function() {
+if (--times > 0) {
+memo = func.apply(this, arguments);
+}
+if (times <= 1) func = null;
+return memo;
+};
+};
+// Returns a function that will be executed at most one time, no matter how
+// often you call it. Useful for lazy initialization.
+_.once = _.partial(_.before, 2);
 // Object Functions
 // ----------------
-// Retrieve the names of an object's properties.
+// Keys in IE < 9 that won't be iterated by `for key in ...` and thus missed.
+var hasEnumBug = !{toString: null}.propertyIsEnumerable('toString');
+var nonEnumerableProps = ['valueOf', 'isPrototypeOf', 'toString',
+'propertyIsEnumerable', 'hasOwnProperty', 'toLocaleString'];
+function collectNonEnumProps(obj, keys) {
+var nonEnumIdx = nonEnumerableProps.length;
+var constructor = obj.constructor;
+var proto = (_.isFunction(constructor) && constructor.prototype) || ObjProto;
+// Constructor is a special case.
+var prop = 'constructor';
+if (_.has(obj, prop) && !_.contains(keys, prop)) keys.push(prop);
+while (nonEnumIdx--) {
+prop = nonEnumerableProps[nonEnumIdx];
+if (prop in obj && obj[prop] !== proto[prop] && !_.contains(keys, prop)) {
+keys.push(prop);
+}
+}
+}
+// Retrieve the names of an object's own properties.
 // Delegates to **ECMAScript 5**'s native `Object.keys`
-_.keys = nativeKeys || function(obj) {
+_.keys = function(obj) {
-if (obj !== Object(obj)) throw new TypeError('Invalid object');
+if (!_.isObject(obj)) return [];
+if (nativeKeys) return nativeKeys(obj);
 var keys = [];
 for (var key in obj) if (_.has(obj, key)) keys.push(key);
+// Ahem, IE < 9.
+if (hasEnumBug) collectNonEnumProps(obj, keys);
+return keys;
+};
+// Retrieve all the property names of an object.
+_.allKeys = function(obj) {
+if (!_.isObject(obj)) return [];
+var keys = [];
+for (var key in obj) keys.push(key);
+// Ahem, IE < 9.
+if (hasEnumBug) collectNonEnumProps(obj, keys);
 return keys;
 };
 // Retrieve the values of an object's properties.
 _.values = function(obj) {
 var keys = _.keys(obj);
 var length = keys.length;
-var values = new Array(length);
+var values = Array(length);
 for (var i = 0; i < length; i++) {
 values[i] = obj[keys[i]];
 }
 return values;
+};
+// Returns the results of applying the iteratee to each element of the object
+// In contrast to _.map it returns an object
+_.mapObject = function(obj, iteratee, context) {
+iteratee = cb(iteratee, context);
+var keys =  _.keys(obj),
+length = keys.length,
+results = {},
+currentKey;
+for (var index = 0; index < length; index++) {
+currentKey = keys[index];
+results[currentKey] = iteratee(obj[currentKey], currentKey, obj);
+}
+return results;
 };
 // Convert an object into a list of `[key, value]` pairs.
 _.pairs = function(obj) {
 var keys = _.keys(obj);
 var length = keys.length;
-var pairs = new Array(length);
+var pairs = Array(length);
 for (var i = 0; i < length; i++) {
 pairs[i] = [keys[i], obj[keys[i]]];
 }
 return pairs;
 };
 }
 return names.sort();
 };
 // Extend a given object with all the properties in passed-in object(s).
-_.extend = function(obj) {
+_.extend = createAssigner(_.allKeys);
-each(slice.call(arguments, 1), function(source) {
-if (source) {
+// Assigns a given object with all the own properties in the passed-in object(s)
-for (var prop in source) {
+// (https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object/assign)
-obj[prop] = source[prop];
+_.extendOwn = _.assign = createAssigner(_.keys);
-}
-}
+// Returns the first key on an object that passes a predicate test
-});
+_.findKey = function(obj, predicate, context) {
-return obj;
+predicate = cb(predicate, context);
+var keys = _.keys(obj), key;
+for (var i = 0, length = keys.length; i < length; i++) {
+key = keys[i];
+if (predicate(obj[key], key, obj)) return key;
+}
 };
 // Return a copy of the object only containing the whitelisted properties.
-_.pick = function(obj) {
+_.pick = function(object, oiteratee, context) {
-var copy = {};
+var result = {}, obj = object, iteratee, keys;
-var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
+if (obj == null) return result;
-each(keys, function(key) {
+if (_.isFunction(oiteratee)) {
-if (key in obj) copy[key] = obj[key];
+keys = _.allKeys(obj);
-});
+iteratee = optimizeCb(oiteratee, context);
-return copy;
+} else {
+keys = flatten(arguments, false, false, 1);
+iteratee = function(value, key, obj) { return key in obj; };
+obj = Object(obj);
+}
+for (var i = 0, length = keys.length; i < length; i++) {
+var key = keys[i];
+var value = obj[key];
+if (iteratee(value, key, obj)) result[key] = value;
+}
+return result;
 };
 // Return a copy of the object without the blacklisted properties.
-_.omit = function(obj) {
+_.omit = function(obj, iteratee, context) {
-var copy = {};
+if (_.isFunction(iteratee)) {
-var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
+iteratee = _.negate(iteratee);
-for (var key in obj) {
+} else {
-if (!_.contains(keys, key)) copy[key] = obj[key];
+var keys = _.map(flatten(arguments, false, false, 1), String);
-}
+iteratee = function(value, key) {
-return copy;
+return !_.contains(keys, key);
+};
+}
+return _.pick(obj, iteratee, context);
 };
 // Fill in a given object with default properties.
-_.defaults = function(obj) {
+_.defaults = createAssigner(_.allKeys, true);
-each(slice.call(arguments, 1), function(source) {
-if (source) {
+// Creates an object that inherits from the given prototype object.
-for (var prop in source) {
+// If additional properties are provided then they will be added to the
-if (obj[prop] === void 0) obj[prop] = source[prop];
+// created object.
-}
+_.create = function(prototype, props) {
-}
+var result = baseCreate(prototype);
-});
+if (props) _.extendOwn(result, props);
-return obj;
+return result;
 };
 // Create a (shallow-cloned) duplicate of an object.
 _.clone = function(obj) {
 if (!_.isObject(obj)) return obj;
 _.tap = function(obj, interceptor) {
 interceptor(obj);
 return obj;
 };
+// Returns whether an object has a given set of `key:value` pairs.
+_.isMatch = function(object, attrs) {
+var keys = _.keys(attrs), length = keys.length;
+if (object == null) return !length;
+var obj = Object(object);
+for (var i = 0; i < length; i++) {
+var key = keys[i];
+if (attrs[key] !== obj[key] || !(key in obj)) return false;
+}
+return true;
+};
 // Internal recursive comparison function for `isEqual`.
 var eq = function(a, b, aStack, bStack) {
 // Identical objects are equal. `0 === -0`, but they aren't identical.
 // See the [Harmony `egal` proposal](http://wiki.ecmascript.org/doku.php?id=harmony:egal).
-if (a === b) return a !== 0 || 1 / a == 1 / b;
+if (a === b) return a !== 0 || 1 / a === 1 / b;
 // A strict comparison is necessary because `null == undefined`.
 if (a == null || b == null) return a === b;
 // Unwrap any wrapped objects.
 if (a instanceof _) a = a._wrapped;
 if (b instanceof _) b = b._wrapped;
 // Compare `[[Class]]` names.
 var className = toString.call(a);
-if (className != toString.call(b)) return false;
+if (className !== toString.call(b)) return false;
 switch (className) {
-// Strings, numbers, dates, and booleans are compared by value.
+// Strings, numbers, regular expressions, dates, and booleans are compared by value.
+case '[object RegExp]':
+// RegExps are coerced to strings for comparison (Note: '' + /a/i === '/a/i')
 case '[object String]':
 // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
 // equivalent to `new String("5")`.
-return a == String(b);
+return '' + a === '' + b;
 case '[object Number]':
-// `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for
+// `NaN`s are equivalent, but non-reflexive.
-// other numeric values.
+// Object(NaN) is equivalent to NaN
-return a != +a ? b != +b : (a == 0 ? 1 / a == 1 / b : a == +b);
+if (+a !== +a) return +b !== +b;
+// An `egal` comparison is performed for other numeric values.
+return +a === 0 ? 1 / +a === 1 / b : +a === +b;
 case '[object Date]':
 case '[object Boolean]':
 // Coerce dates and booleans to numeric primitive values. Dates are compared by their
 // millisecond representations. Note that invalid dates with millisecond representations
 // of `NaN` are not equivalent.
-return +a == +b;
+return +a === +b;
-// RegExps are compared by their source patterns and flags.
+}
-case '[object RegExp]':
-return a.source == b.source &&
+var areArrays = className === '[object Array]';
-a.global == b.global &&
+if (!areArrays) {
-a.multiline == b.multiline &&
+if (typeof a != 'object' || typeof b != 'object') return false;
-a.ignoreCase == b.ignoreCase;
-}
+// Objects with different constructors are not equivalent, but `Object`s or `Array`s
-if (typeof a != 'object' || typeof b != 'object') return false;
+// from different frames are.
+var aCtor = a.constructor, bCtor = b.constructor;
+if (aCtor !== bCtor && !(_.isFunction(aCtor) && aCtor instanceof aCtor &&
+_.isFunction(bCtor) && bCtor instanceof bCtor)
+&& ('constructor' in a && 'constructor' in b)) {
+return false;
+}
+}
 // Assume equality for cyclic structures. The algorithm for detecting cyclic
 // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
+// Initializing stack of traversed objects.
+// It's done here since we only need them for objects and arrays comparison.
+aStack = aStack || [];
+bStack = bStack || [];
 var length = aStack.length;
 while (length--) {
 // Linear search. Performance is inversely proportional to the number of
 // unique nested structures.
-if (aStack[length] == a) return bStack[length] == b;
+if (aStack[length] === a) return bStack[length] === b;
 }
-// Objects with different constructors are not equivalent, but `Object`s
-// from different frames are.
-var aCtor = a.constructor, bCtor = b.constructor;
-if (aCtor !== bCtor && !(_.isFunction(aCtor) && (aCtor instanceof aCtor) &&
-_.isFunction(bCtor) && (bCtor instanceof bCtor))) {
-return false;
-}
 // Add the first object to the stack of traversed objects.
 aStack.push(a);
 bStack.push(b);
-var size = 0, result = true;
 // Recursively compare objects and arrays.
-if (className == '[object Array]') {
+if (areArrays) {
 // Compare array lengths to determine if a deep comparison is necessary.
-size = a.length;
+length = a.length;
-result = size == b.length;
+if (length !== b.length) return false;
-if (result) {
+// Deep compare the contents, ignoring non-numeric properties.
-// Deep compare the contents, ignoring non-numeric properties.
+while (length--) {
-while (size--) {
+if (!eq(a[length], b[length], aStack, bStack)) return false;
-if (!(result = eq(a[size], b[size], aStack, bStack))) break;
-}
 }
 } else {
 // Deep compare objects.
-for (var key in a) {
+var keys = _.keys(a), key;
-if (_.has(a, key)) {
+length = keys.length;
-// Count the expected number of properties.
+// Ensure that both objects contain the same number of properties before comparing deep equality.
-size++;
+if (_.keys(b).length !== length) return false;
-// Deep compare each member.
+while (length--) {
-if (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) break;
+// Deep compare each member
-}
+key = keys[length];
-}
+if (!(_.has(b, key) && eq(a[key], b[key], aStack, bStack))) return false;
-// Ensure that both objects contain the same number of properties.
-if (result) {
-for (key in b) {
-if (_.has(b, key) && !(size--)) break;
-}
-result = !size;
 }
 }
 // Remove the first object from the stack of traversed objects.
 aStack.pop();
 bStack.pop();
-return result;
+return true;
 };
 // Perform a deep comparison to check if two objects are equal.
 _.isEqual = function(a, b) {
-return eq(a, b, [], []);
+return eq(a, b);
 };
 // Is a given array, string, or object empty?
 // An "empty" object has no enumerable own-properties.
 _.isEmpty = function(obj) {
 if (obj == null) return true;
-if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
+if (isArrayLike(obj) && (_.isArray(obj) || _.isString(obj) || _.isArguments(obj))) return obj.length === 0;
-for (var key in obj) if (_.has(obj, key)) return false;
+return _.keys(obj).length === 0;
-return true;
 };
 // Is a given value a DOM element?
 _.isElement = function(obj) {
 return !!(obj && obj.nodeType === 1);
 };
 // Is a given value an array?
 // Delegates to ECMA5's native Array.isArray
 _.isArray = nativeIsArray || function(obj) {
-return toString.call(obj) == '[object Array]';
+return toString.call(obj) === '[object Array]';
 };
 // Is a given variable an object?
 _.isObject = function(obj) {
-return obj === Object(obj);
+var type = typeof obj;
-};
+return type === 'function' || type === 'object' && !!obj;
+};
-// Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp.
-each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp'], function(name) {
+// Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp, isError.
+_.each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp', 'Error'], function(name) {
 _['is' + name] = function(obj) {
-return toString.call(obj) == '[object ' + name + ']';
+return toString.call(obj) === '[object ' + name + ']';
 };
 });
-// Define a fallback version of the method in browsers (ahem, IE), where
+// Define a fallback version of the method in browsers (ahem, IE < 9), where
 // there isn't any inspectable "Arguments" type.
 if (!_.isArguments(arguments)) {
 _.isArguments = function(obj) {
-return !!(obj && _.has(obj, 'callee'));
+return _.has(obj, 'callee');
 };
 }
-// Optimize `isFunction` if appropriate.
+// Optimize `isFunction` if appropriate. Work around some typeof bugs in old v8,
-if (typeof (/./) !== 'function') {
+// IE 11 (#1621), and in Safari 8 (#1929).
+if (typeof /./ != 'function' && typeof Int8Array != 'object') {
 _.isFunction = function(obj) {
-return typeof obj === 'function';
+return typeof obj == 'function' || false;
 };
 }
 // Is a given object a finite number?
 _.isFinite = function(obj) {
 return isFinite(obj) && !isNaN(parseFloat(obj));
 };
 // Is the given value `NaN`? (NaN is the only number which does not equal itself).
 _.isNaN = function(obj) {
-return _.isNumber(obj) && obj != +obj;
+return _.isNumber(obj) && obj !== +obj;
 };
 // Is a given value a boolean?
 _.isBoolean = function(obj) {
-return obj === true || obj === false || toString.call(obj) == '[object Boolean]';
+return obj === true || obj === false || toString.call(obj) === '[object Boolean]';
 };
 // Is a given value equal to null?
 _.isNull = function(obj) {
 return obj === null;
 };
 // Shortcut function for checking if an object has a given property directly
 // on itself (in other words, not on a prototype).
 _.has = function(obj, key) {
-return hasOwnProperty.call(obj, key);
+return obj != null && hasOwnProperty.call(obj, key);
 };
 // Utility Functions
 // -----------------
 _.noConflict = function() {
 root._ = previousUnderscore;
 return this;
 };
-// Keep the identity function around for default iterators.
+// Keep the identity function around for default iteratees.
 _.identity = function(value) {
 return value;
 };
+// Predicate-generating functions. Often useful outside of Underscore.
+_.constant = function(value) {
+return function() {
+return value;
+};
+};
+_.noop = function(){};
+_.property = property;
+// Generates a function for a given object that returns a given property.
+_.propertyOf = function(obj) {
+return obj == null ? function(){} : function(key) {
+return obj[key];
+};
+};
+// Returns a predicate for checking whether an object has a given set of
+// `key:value` pairs.
+_.matcher = _.matches = function(attrs) {
+attrs = _.extendOwn({}, attrs);
+return function(obj) {
+return _.isMatch(obj, attrs);
+};
+};
 // Run a function **n** times.
-_.times = function(n, iterator, context) {
+_.times = function(n, iteratee, context) {
 var accum = Array(Math.max(0, n));
-for (var i = 0; i < n; i++) accum[i] = iterator.call(context, i);
+iteratee = optimizeCb(iteratee, context, 1);
+for (var i = 0; i < n; i++) accum[i] = iteratee(i);
 return accum;
 };
 // Return a random integer between min and max (inclusive).
 _.random = function(min, max) {
 min = 0;
 }
 return min + Math.floor(Math.random() * (max - min + 1));
 };
-// List of HTML entities for escaping.
+// A (possibly faster) way to get the current timestamp as an integer.
-var entityMap = {
+_.now = Date.now || function() {
-escape: {
+return new Date().getTime();
-'&': '&amp;',
+};
-'<': '&lt;',
-'>': '&gt;',
+// List of HTML entities for escaping.
-'"': '&quot;',
+var escapeMap = {
-"'": '&#x27;'
+'&': '&amp;',
-}
+'<': '&lt;',
-};
+'>': '&gt;',
-entityMap.unescape = _.invert(entityMap.escape);
+'"': '&quot;',
+"'": '&#x27;',
-// Regexes containing the keys and values listed immediately above.
+'`': '&#x60;'
-var entityRegexes = {
+};
-escape:   new RegExp('[' + _.keys(entityMap.escape).join('') + ']', 'g'),
+var unescapeMap = _.invert(escapeMap);
-unescape: new RegExp('(' + _.keys(entityMap.unescape).join('|') + ')', 'g')
-};
 // Functions for escaping and unescaping strings to/from HTML interpolation.
-_.each(['escape', 'unescape'], function(method) {
+var createEscaper = function(map) {
-_[method] = function(string) {
+var escaper = function(match) {
-if (string == null) return '';
+return map[match];
-return ('' + string).replace(entityRegexes[method], function(match) {
+};
-return entityMap[method][match];
+// Regexes for identifying a key that needs to be escaped
-});
+var source = '(?:' + _.keys(map).join('|') + ')';
-};
+var testRegexp = RegExp(source);
-});
+var replaceRegexp = RegExp(source, 'g');
+return function(string) {
+string = string == null ? '' : '' + string;
+return testRegexp.test(string) ? string.replace(replaceRegexp, escaper) : string;
+};
+};
+_.escape = createEscaper(escapeMap);
+_.unescape = createEscaper(unescapeMap);
 // If the value of the named `property` is a function then invoke it with the
 // `object` as context; otherwise, return it.
-_.result = function(object, property) {
+_.result = function(object, property, fallback) {
-if (object == null) return void 0;
+var value = object == null ? void 0 : object[property];
-var value = object[property];
+if (value === void 0) {
+value = fallback;
+}
 return _.isFunction(value) ? value.call(object) : value;
-};
-// Add your own custom functions to the Underscore object.
-_.mixin = function(obj) {
-each(_.functions(obj), function(name) {
-var func = _[name] = obj[name];
-_.prototype[name] = function() {
-var args = [this._wrapped];
-push.apply(args, arguments);
-return result.call(this, func.apply(_, args));
-};
-});
 };
 // Generate a unique integer id (unique within the entire client session).
 // Useful for temporary DOM ids.
 var idCounter = 0;
 var escapes = {
 "'":      "'",
 '\\':     '\\',
 '\r':     'r',
 '\n':     'n',
-'\t':     't',
 '\u2028': 'u2028',
 '\u2029': 'u2029'
 };
-var escaper = /\\|'|\r|\n|\t|\u2028|\u2029/g;
+var escaper = /\\|'|\r|\n|\u2028|\u2029/g;
+var escapeChar = function(match) {
+return '\\' + escapes[match];
+};
 // JavaScript micro-templating, similar to John Resig's implementation.
 // Underscore templating handles arbitrary delimiters, preserves whitespace,
 // and correctly escapes quotes within interpolated code.
-_.template = function(text, data, settings) {
+// NB: `oldSettings` only exists for backwards compatibility.
-var render;
+_.template = function(text, settings, oldSettings) {
+if (!settings && oldSettings) settings = oldSettings;
 settings = _.defaults({}, settings, _.templateSettings);
 // Combine delimiters into one regular expression via alternation.
-var matcher = new RegExp([
+var matcher = RegExp([
 (settings.escape || noMatch).source,
 (settings.interpolate || noMatch).source,
 (settings.evaluate || noMatch).source
 ].join('|') + '|$', 'g');
 // Compile the template source, escaping string literals appropriately.
 var index = 0;
 var source = "__p+='";
 text.replace(matcher, function(match, escape, interpolate, evaluate, offset) {
-source += text.slice(index, offset)
+source += text.slice(index, offset).replace(escaper, escapeChar);
-.replace(escaper, function(match) { return '\\' + escapes[match]; });
+index = offset + match.length;
 if (escape) {
 source += "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'";
-}
+} else if (interpolate) {
-if (interpolate) {
 source += "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'";
-}
+} else if (evaluate) {
-if (evaluate) {
 source += "';\n" + evaluate + "\n__p+='";
 }
-index = offset + match.length;
+// Adobe VMs need the match returned to produce the correct offest.
 return match;
 });
 source += "';\n";
 // If a variable is not specified, place data values in local scope.
 if (!settings.variable) source = 'with(obj||{}){\n' + source + '}\n';
 source = "var __t,__p='',__j=Array.prototype.join," +
 "print=function(){__p+=__j.call(arguments,'');};\n" +
-source + "return __p;\n";
+source + 'return __p;\n';
 try {
-render = new Function(settings.variable || 'obj', '_', source);
+var render = new Function(settings.variable || 'obj', '_', source);
 } catch (e) {
 e.source = source;
 throw e;
 }
-if (data) return render(data, _);
 var template = function(data) {
 return render.call(this, data, _);
 };
-// Provide the compiled function source as a convenience for precompilation.
+// Provide the compiled source as a convenience for precompilation.
-template.source = 'function(' + (settings.variable || 'obj') + '){\n' + source + '}';
+var argument = settings.variable || 'obj';
+template.source = 'function(' + argument + '){\n' + source + '}';
 return template;
 };
-// Add a "chain" function, which will delegate to the wrapper.
+// Add a "chain" function. Start chaining a wrapped Underscore object.
 _.chain = function(obj) {
-return _(obj).chain();
+var instance = _(obj);
+instance._chain = true;
+return instance;
 };
 // OOP
 // ---------------
 // If Underscore is called as a function, it returns a wrapped object that
 // can be used OO-style. This wrapper holds altered versions of all the
 // underscore functions. Wrapped objects may be chained.
 // Helper function to continue chaining intermediate results.
-var result = function(obj) {
+var result = function(instance, obj) {
-return this._chain ? _(obj).chain() : obj;
+return instance._chain ? _(obj).chain() : obj;
+};
+// Add your own custom functions to the Underscore object.
+_.mixin = function(obj) {
+_.each(_.functions(obj), function(name) {
+var func = _[name] = obj[name];
+_.prototype[name] = function() {
+var args = [this._wrapped];
+push.apply(args, arguments);
+return result(this, func.apply(_, args));
+};
+});
 };
 // Add all of the Underscore functions to the wrapper object.
 _.mixin(_);
 // Add all mutator Array functions to the wrapper.
-each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
+_.each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
 var method = ArrayProto[name];
 _.prototype[name] = function() {
 var obj = this._wrapped;
 method.apply(obj, arguments);
-if ((name == 'shift' || name == 'splice') && obj.length === 0) delete obj[0];
+if ((name === 'shift' || name === 'splice') && obj.length === 0) delete obj[0];
-return result.call(this, obj);
+return result(this, obj);
 };
 });
 // Add all accessor Array functions to the wrapper.
-each(['concat', 'join', 'slice'], function(name) {
+_.each(['concat', 'join', 'slice'], function(name) {
 var method = ArrayProto[name];
 _.prototype[name] = function() {
-return result.call(this, method.apply(this._wrapped, arguments));
+return result(this, method.apply(this._wrapped, arguments));
 };
 });
-_.extend(_.prototype, {
+// Extracts the result from a wrapped and chained object.
+_.prototype.value = function() {
-// Start chaining a wrapped Underscore object.
+return this._wrapped;
-chain: function() {
+};
-this._chain = true;
-return this;
+// Provide unwrapping proxy for some methods used in engine operations
-},
+// such as arithmetic and JSON stringification.
+_.prototype.valueOf = _.prototype.toJSON = _.prototype.value;
-// Extracts the result from a wrapped and chained object.
-value: function() {
+_.prototype.toString = function() {
-return this._wrapped;
+return '' + this._wrapped;
-}
+};
-});
+// AMD registration happens at the end for compatibility with AMD loaders
+// that may not enforce next-turn semantics on modules. Even though general
-}).call(this);
+// practice for AMD registration is to be anonymous, underscore registers
+// as a named module because, like jQuery, it is a base library that is
+// popular enough to be bundled in a third party lib, but not be part of
+// an AMD load request. Those cases could generate an error when an
+// anonymous define() is called outside of a loader request.
+if (typeof define === 'function' && define.amd) {
+define('underscore', [], function() {
+return _;
+});
+}
+}.call(this));

tweet_live