2 // (c) 2011 Jeremy Ashkenas, DocumentCloud Inc.
3 // Underscore is freely distributable under the MIT license.
4 // Portions of Underscore are inspired or borrowed from Prototype,
5 // Oliver Steele's Functional, and John Resig's Micro-Templating.
6 // For all details and documentation:
7 // http://documentcloud.github.com/underscore
14 // Establish the root object, `window` in the browser, or `global` on the server.
17 // Save the previous value of the `_` variable.
18 var previousUnderscore = root._;
20 // Establish the object that gets returned to break out of a loop iteration.
23 // Save bytes in the minified (but not gzipped) version:
24 var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;
26 // Create quick reference variables for speed access to core prototypes.
27 var slice = ArrayProto.slice,
28 unshift = ArrayProto.unshift,
29 toString = ObjProto.toString,
30 hasOwnProperty = ObjProto.hasOwnProperty;
32 // All **ECMAScript 5** native function implementations that we hope to use
35 nativeForEach = ArrayProto.forEach,
36 nativeMap = ArrayProto.map,
37 nativeReduce = ArrayProto.reduce,
38 nativeReduceRight = ArrayProto.reduceRight,
39 nativeFilter = ArrayProto.filter,
40 nativeEvery = ArrayProto.every,
41 nativeSome = ArrayProto.some,
42 nativeIndexOf = ArrayProto.indexOf,
43 nativeLastIndexOf = ArrayProto.lastIndexOf,
44 nativeIsArray = Array.isArray,
45 nativeKeys = Object.keys,
46 nativeBind = FuncProto.bind;
48 // Create a safe reference to the Underscore object for use below.
49 var _ = function(obj) { return new wrapper(obj); };
51 // Export the Underscore object for **CommonJS**, with backwards-compatibility
52 // for the old `require()` API. If we're not in CommonJS, add `_` to the
54 if (typeof module !== 'undefined' && module.exports) {
58 // Exported as a string, for Closure Compiler "advanced" mode.
65 // Collection Functions
66 // --------------------
68 // The cornerstone, an `each` implementation, aka `forEach`.
69 // Handles objects with the built-in `forEach`, arrays, and raw objects.
70 // Delegates to **ECMAScript 5**'s native `forEach` if available.
71 var each = _.each = _.forEach = function(obj, iterator, context) {
72 if (obj == null) return;
73 if (nativeForEach && obj.forEach === nativeForEach) {
74 obj.forEach(iterator, context);
75 } else if (obj.length === +obj.length) {
76 for (var i = 0, l = obj.length; i < l; i++) {
77 if (i in obj && iterator.call(context, obj[i], i, obj) === breaker) return;
80 for (var key in obj) {
81 if (hasOwnProperty.call(obj, key)) {
82 if (iterator.call(context, obj[key], key, obj) === breaker) return;
88 // Return the results of applying the iterator to each element.
89 // Delegates to **ECMAScript 5**'s native `map` if available.
90 _.map = function(obj, iterator, context) {
92 if (obj == null) return results;
93 if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
94 each(obj, function(value, index, list) {
95 results[results.length] = iterator.call(context, value, index, list);
100 // **Reduce** builds up a single result from a list of values, aka `inject`,
101 // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
102 _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
103 var initial = memo !== void 0;
104 if (obj == null) obj = [];
105 if (nativeReduce && obj.reduce === nativeReduce) {
106 if (context) iterator = _.bind(iterator, context);
107 return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
109 each(obj, function(value, index, list) {
114 memo = iterator.call(context, memo, value, index, list);
117 if (!initial) throw new TypeError("Reduce of empty array with no initial value");
121 // The right-associative version of reduce, also known as `foldr`.
122 // Delegates to **ECMAScript 5**'s native `reduceRight` if available.
123 _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
124 if (obj == null) obj = [];
125 if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
126 if (context) iterator = _.bind(iterator, context);
127 return memo !== void 0 ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
129 var reversed = (_.isArray(obj) ? obj.slice() : _.toArray(obj)).reverse();
130 return _.reduce(reversed, iterator, memo, context);
133 // Return the first value which passes a truth test. Aliased as `detect`.
134 _.find = _.detect = function(obj, iterator, context) {
136 any(obj, function(value, index, list) {
137 if (iterator.call(context, value, index, list)) {
145 // Return all the elements that pass a truth test.
146 // Delegates to **ECMAScript 5**'s native `filter` if available.
147 // Aliased as `select`.
148 _.filter = _.select = function(obj, iterator, context) {
150 if (obj == null) return results;
151 if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
152 each(obj, function(value, index, list) {
153 if (iterator.call(context, value, index, list)) results[results.length] = value;
158 // Return all the elements for which a truth test fails.
159 _.reject = function(obj, iterator, context) {
161 if (obj == null) return results;
162 each(obj, function(value, index, list) {
163 if (!iterator.call(context, value, index, list)) results[results.length] = value;
168 // Determine whether all of the elements match a truth test.
169 // Delegates to **ECMAScript 5**'s native `every` if available.
171 _.every = _.all = function(obj, iterator, context) {
173 if (obj == null) return result;
174 if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
175 each(obj, function(value, index, list) {
176 if (!(result = result && iterator.call(context, value, index, list))) return breaker;
181 // Determine if at least one element in the object matches a truth test.
182 // Delegates to **ECMAScript 5**'s native `some` if available.
184 var any = _.some = _.any = function(obj, iterator, context) {
185 iterator = iterator || _.identity;
187 if (obj == null) return result;
188 if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
189 each(obj, function(value, index, list) {
190 if (result |= iterator.call(context, value, index, list)) return breaker;
195 // Determine if a given value is included in the array or object using `===`.
196 // Aliased as `contains`.
197 _.include = _.contains = function(obj, target) {
199 if (obj == null) return found;
200 if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
201 any(obj, function(value) {
202 if (found = value === target) return true;
207 // Invoke a method (with arguments) on every item in a collection.
208 _.invoke = function(obj, method) {
209 var args = slice.call(arguments, 2);
210 return _.map(obj, function(value) {
211 return (method.call ? method || value : value[method]).apply(value, args);
215 // Convenience version of a common use case of `map`: fetching a property.
216 _.pluck = function(obj, key) {
217 return _.map(obj, function(value){ return value[key]; });
220 // Return the maximum element or (element-based computation).
221 _.max = function(obj, iterator, context) {
222 if (!iterator && _.isArray(obj)) return Math.max.apply(Math, obj);
223 var result = {computed : -Infinity};
224 each(obj, function(value, index, list) {
225 var computed = iterator ? iterator.call(context, value, index, list) : value;
226 computed >= result.computed && (result = {value : value, computed : computed});
231 // Return the minimum element (or element-based computation).
232 _.min = function(obj, iterator, context) {
233 if (!iterator && _.isArray(obj)) return Math.min.apply(Math, obj);
234 var result = {computed : Infinity};
235 each(obj, function(value, index, list) {
236 var computed = iterator ? iterator.call(context, value, index, list) : value;
237 computed < result.computed && (result = {value : value, computed : computed});
242 // Sort the object's values by a criterion produced by an iterator.
243 _.sortBy = function(obj, iterator, context) {
244 return _.pluck(_.map(obj, function(value, index, list) {
247 criteria : iterator.call(context, value, index, list)
249 }).sort(function(left, right) {
250 var a = left.criteria, b = right.criteria;
251 return a < b ? -1 : a > b ? 1 : 0;
255 // Groups the object's values by a criterion produced by an iterator
256 _.groupBy = function(obj, iterator) {
258 each(obj, function(value, index) {
259 var key = iterator(value, index);
260 (result[key] || (result[key] = [])).push(value);
265 // Use a comparator function to figure out at what index an object should
266 // be inserted so as to maintain order. Uses binary search.
267 _.sortedIndex = function(array, obj, iterator) {
268 iterator || (iterator = _.identity);
269 var low = 0, high = array.length;
271 var mid = (low + high) >> 1;
272 iterator(array[mid]) < iterator(obj) ? low = mid + 1 : high = mid;
277 // Safely convert anything iterable into a real, live array.
278 _.toArray = function(iterable) {
279 if (!iterable) return [];
280 if (iterable.toArray) return iterable.toArray();
281 if (_.isArray(iterable)) return slice.call(iterable);
282 if (_.isArguments(iterable)) return slice.call(iterable);
283 return _.values(iterable);
286 // Return the number of elements in an object.
287 _.size = function(obj) {
288 return _.toArray(obj).length;
294 // Get the first element of an array. Passing **n** will return the first N
295 // values in the array. Aliased as `head`. The **guard** check allows it to work
297 _.first = _.head = function(array, n, guard) {
298 return (n != null) && !guard ? slice.call(array, 0, n) : array[0];
301 // Returns everything but the first entry of the array. Aliased as `tail`.
302 // Especially useful on the arguments object. Passing an **index** will return
303 // the rest of the values in the array from that index onward. The **guard**
304 // check allows it to work with `_.map`.
305 _.rest = _.tail = function(array, index, guard) {
306 return slice.call(array, (index == null) || guard ? 1 : index);
309 // Get the last element of an array.
310 _.last = function(array) {
311 return array[array.length - 1];
314 // Trim out all falsy values from an array.
315 _.compact = function(array) {
316 return _.filter(array, function(value){ return !!value; });
319 // Return a completely flattened version of an array.
320 _.flatten = function(array) {
321 return _.reduce(array, function(memo, value) {
322 if (_.isArray(value)) return memo.concat(_.flatten(value));
323 memo[memo.length] = value;
328 // Return a version of the array that does not contain the specified value(s).
329 _.without = function(array) {
330 return _.difference(array, slice.call(arguments, 1));
333 // Produce a duplicate-free version of the array. If the array has already
334 // been sorted, you have the option of using a faster algorithm.
335 // Aliased as `unique`.
336 _.uniq = _.unique = function(array, isSorted) {
337 return _.reduce(array, function(memo, el, i) {
338 if (0 == i || (isSorted === true ? _.last(memo) != el : !_.include(memo, el))) memo[memo.length] = el;
343 // Produce an array that contains the union: each distinct element from all of
344 // the passed-in arrays.
345 _.union = function() {
346 return _.uniq(_.flatten(arguments));
349 // Produce an array that contains every item shared between all the
350 // passed-in arrays. (Aliased as "intersect" for back-compat.)
351 _.intersection = _.intersect = function(array) {
352 var rest = slice.call(arguments, 1);
353 return _.filter(_.uniq(array), function(item) {
354 return _.every(rest, function(other) {
355 return _.indexOf(other, item) >= 0;
360 // Take the difference between one array and another.
361 // Only the elements present in just the first array will remain.
362 _.difference = function(array, other) {
363 return _.filter(array, function(value){ return !_.include(other, value); });
366 // Zip together multiple lists into a single array -- elements that share
367 // an index go together.
369 var args = slice.call(arguments);
370 var length = _.max(_.pluck(args, 'length'));
371 var results = new Array(length);
372 for (var i = 0; i < length; i++) results[i] = _.pluck(args, "" + i);
376 // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
377 // we need this function. Return the position of the first occurrence of an
378 // item in an array, or -1 if the item is not included in the array.
379 // Delegates to **ECMAScript 5**'s native `indexOf` if available.
380 // If the array is large and already in sort order, pass `true`
381 // for **isSorted** to use binary search.
382 _.indexOf = function(array, item, isSorted) {
383 if (array == null) return -1;
386 i = _.sortedIndex(array, item);
387 return array[i] === item ? i : -1;
389 if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);
390 for (i = 0, l = array.length; i < l; i++) if (array[i] === item) return i;
395 // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
396 _.lastIndexOf = function(array, item) {
397 if (array == null) return -1;
398 if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);
399 var i = array.length;
400 while (i--) if (array[i] === item) return i;
404 // Generate an integer Array containing an arithmetic progression. A port of
405 // the native Python `range()` function. See
406 // [the Python documentation](http://docs.python.org/library/functions.html#range).
407 _.range = function(start, stop, step) {
408 if (arguments.length <= 1) {
412 step = arguments[2] || 1;
414 var len = Math.max(Math.ceil((stop - start) / step), 0);
416 var range = new Array(len);
419 range[idx++] = start;
426 // Function (ahem) Functions
427 // ------------------
429 // Create a function bound to a given object (assigning `this`, and arguments,
430 // optionally). Binding with arguments is also known as `curry`.
431 // Delegates to **ECMAScript 5**'s native `Function.bind` if available.
432 // We check for `func.bind` first, to fail fast when `func` is undefined.
433 _.bind = function(func, obj) {
434 if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
435 var args = slice.call(arguments, 2);
437 return func.apply(obj, args.concat(slice.call(arguments)));
441 // Bind all of an object's methods to that object. Useful for ensuring that
442 // all callbacks defined on an object belong to it.
443 _.bindAll = function(obj) {
444 var funcs = slice.call(arguments, 1);
445 if (funcs.length == 0) funcs = _.functions(obj);
446 each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
450 // Memoize an expensive function by storing its results.
451 _.memoize = function(func, hasher) {
453 hasher || (hasher = _.identity);
455 var key = hasher.apply(this, arguments);
456 return hasOwnProperty.call(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
460 // Delays a function for the given number of milliseconds, and then calls
461 // it with the arguments supplied.
462 _.delay = function(func, wait) {
463 var args = slice.call(arguments, 2);
464 return setTimeout(function(){ return func.apply(func, args); }, wait);
467 // Defers a function, scheduling it to run after the current call stack has
469 _.defer = function(func) {
470 return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
473 // Internal function used to implement `_.throttle` and `_.debounce`.
474 var limit = function(func, wait, debounce) {
477 var context = this, args = arguments;
478 var throttler = function() {
480 func.apply(context, args);
482 if (debounce) clearTimeout(timeout);
483 if (debounce || !timeout) timeout = setTimeout(throttler, wait);
487 // Returns a function, that, when invoked, will only be triggered at most once
488 // during a given window of time.
489 _.throttle = function(func, wait) {
490 return limit(func, wait, false);
493 // Returns a function, that, as long as it continues to be invoked, will not
494 // be triggered. The function will be called after it stops being called for
496 _.debounce = function(func, wait) {
497 return limit(func, wait, true);
500 // Returns a function that will be executed at most one time, no matter how
501 // often you call it. Useful for lazy initialization.
502 _.once = function(func) {
503 var ran = false, memo;
505 if (ran) return memo;
507 memo = func.apply(this, arguments);
512 // Returns the first function passed as an argument to the second,
513 // allowing you to adjust arguments, run code before and after, and
514 // conditionally execute the original function.
515 _.wrap = function(func, wrapper) {
517 var args = [func].concat(slice.call(arguments));
518 return wrapper.apply(this, args);
522 // Returns a function that is the composition of a list of functions, each
523 // consuming the return value of the function that follows.
524 _.compose = function() {
525 var funcs = slice.call(arguments);
527 var args = slice.call(arguments);
528 for (var i = funcs.length - 1; i >= 0; i--) {
529 args = [funcs[i].apply(this, args)];
535 // Returns a function that will only be executed after being called N times.
536 _.after = function(times, func) {
538 if (--times < 1) { return func.apply(this, arguments); }
546 // Retrieve the names of an object's properties.
547 // Delegates to **ECMAScript 5**'s native `Object.keys`
548 _.keys = nativeKeys || function(obj) {
549 if (obj !== Object(obj)) throw new TypeError('Invalid object');
551 for (var key in obj) if (hasOwnProperty.call(obj, key)) keys[keys.length] = key;
555 // Retrieve the values of an object's properties.
556 _.values = function(obj) {
557 return _.map(obj, _.identity);
560 // Return a sorted list of the function names available on the object.
561 // Aliased as `methods`
562 _.functions = _.methods = function(obj) {
564 for (var key in obj) {
565 if (_.isFunction(obj[key])) names.push(key);
570 // Extend a given object with all the properties in passed-in object(s).
571 _.extend = function(obj) {
572 each(slice.call(arguments, 1), function(source) {
573 for (var prop in source) {
574 if (source[prop] !== void 0) obj[prop] = source[prop];
580 // Fill in a given object with default properties.
581 _.defaults = function(obj) {
582 each(slice.call(arguments, 1), function(source) {
583 for (var prop in source) {
584 if (obj[prop] == null) obj[prop] = source[prop];
590 // Create a (shallow-cloned) duplicate of an object.
591 _.clone = function(obj) {
592 return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
595 // Invokes interceptor with the obj, and then returns obj.
596 // The primary purpose of this method is to "tap into" a method chain, in
597 // order to perform operations on intermediate results within the chain.
598 _.tap = function(obj, interceptor) {
603 // Perform a deep comparison to check if two objects are equal.
604 _.isEqual = function(a, b) {
605 // Check object identity.
606 if (a === b) return true;
608 var atype = typeof(a), btype = typeof(b);
609 if (atype != btype) return false;
610 // Basic equality test (watch out for coercions).
611 if (a == b) return true;
612 // One is falsy and the other truthy.
613 if ((!a && b) || (a && !b)) return false;
614 // Unwrap any wrapped objects.
615 if (a._chain) a = a._wrapped;
616 if (b._chain) b = b._wrapped;
617 // One of them implements an isEqual()?
618 if (a.isEqual) return a.isEqual(b);
619 if (b.isEqual) return b.isEqual(a);
620 // Check dates' integer values.
621 if (_.isDate(a) && _.isDate(b)) return a.getTime() === b.getTime();
623 if (_.isNaN(a) && _.isNaN(b)) return false;
624 // Compare regular expressions.
625 if (_.isRegExp(a) && _.isRegExp(b))
626 return a.source === b.source &&
627 a.global === b.global &&
628 a.ignoreCase === b.ignoreCase &&
629 a.multiline === b.multiline;
630 // If a is not an object by this point, we can't handle it.
631 if (atype !== 'object') return false;
632 // Check for different array lengths before comparing contents.
633 if (a.length && (a.length !== b.length)) return false;
634 // Nothing else worked, deep compare the contents.
635 var aKeys = _.keys(a), bKeys = _.keys(b);
636 // Different object sizes?
637 if (aKeys.length != bKeys.length) return false;
638 // Recursive comparison of contents.
639 for (var key in a) if (!(key in b) || !_.isEqual(a[key], b[key])) return false;
643 // Is a given array or object empty?
644 _.isEmpty = function(obj) {
645 if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
646 for (var key in obj) if (hasOwnProperty.call(obj, key)) return false;
650 // Is a given value a DOM element?
651 _.isElement = function(obj) {
652 return !!(obj && obj.nodeType == 1);
655 // Is a given value an array?
656 // Delegates to ECMA5's native Array.isArray
657 _.isArray = nativeIsArray || function(obj) {
658 return toString.call(obj) === '[object Array]';
661 // Is a given variable an object?
662 _.isObject = function(obj) {
663 return obj === Object(obj);
666 // Is a given variable an arguments object?
667 _.isArguments = function(obj) {
668 return !!(obj && hasOwnProperty.call(obj, 'callee'));
671 // Is a given value a function?
672 _.isFunction = function(obj) {
673 return !!(obj && obj.constructor && obj.call && obj.apply);
676 // Is a given value a string?
677 _.isString = function(obj) {
678 return !!(obj === '' || (obj && obj.charCodeAt && obj.substr));
681 // Is a given value a number?
682 _.isNumber = function(obj) {
683 return !!(obj === 0 || (obj && obj.toExponential && obj.toFixed));
686 // Is the given value `NaN`? `NaN` happens to be the only value in JavaScript
687 // that does not equal itself.
688 _.isNaN = function(obj) {
692 // Is a given value a boolean?
693 _.isBoolean = function(obj) {
694 return obj === true || obj === false;
697 // Is a given value a date?
698 _.isDate = function(obj) {
699 return !!(obj && obj.getTimezoneOffset && obj.setUTCFullYear);
702 // Is the given value a regular expression?
703 _.isRegExp = function(obj) {
704 return !!(obj && obj.test && obj.exec && (obj.ignoreCase || obj.ignoreCase === false));
707 // Is a given value equal to null?
708 _.isNull = function(obj) {
712 // Is a given variable undefined?
713 _.isUndefined = function(obj) {
714 return obj === void 0;
720 // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
721 // previous owner. Returns a reference to the Underscore object.
722 _.noConflict = function() {
723 root._ = previousUnderscore;
727 // Keep the identity function around for default iterators.
728 _.identity = function(value) {
732 // Run a function **n** times.
733 _.times = function (n, iterator, context) {
734 for (var i = 0; i < n; i++) iterator.call(context, i);
737 // Add your own custom functions to the Underscore object, ensuring that
738 // they're correctly added to the OOP wrapper as well.
739 _.mixin = function(obj) {
740 each(_.functions(obj), function(name){
741 addToWrapper(name, _[name] = obj[name]);
745 // Generate a unique integer id (unique within the entire client session).
746 // Useful for temporary DOM ids.
748 _.uniqueId = function(prefix) {
749 var id = idCounter++;
750 return prefix ? prefix + id : id;
753 // By default, Underscore uses ERB-style template delimiters, change the
754 // following template settings to use alternative delimiters.
755 _.templateSettings = {
756 evaluate : /<%([\s\S]+?)%>/g,
757 interpolate : /<%=([\s\S]+?)%>/g
760 // JavaScript micro-templating, similar to John Resig's implementation.
761 // Underscore templating handles arbitrary delimiters, preserves whitespace,
762 // and correctly escapes quotes within interpolated code.
763 _.template = function(str, data) {
764 var c = _.templateSettings;
765 var tmpl = 'var __p=[],print=function(){__p.push.apply(__p,arguments);};' +
766 'with(obj||{}){__p.push(\'' +
767 str.replace(/\\/g, '\\\\')
768 .replace(/'/g, "\\'")
769 .replace(c.interpolate, function(match, code) {
770 return "'," + code.replace(/\\'/g, "'") + ",'";
772 .replace(c.evaluate || null, function(match, code) {
773 return "');" + code.replace(/\\'/g, "'")
774 .replace(/[\r\n\t]/g, ' ') + "__p.push('";
776 .replace(/\r/g, '\\r')
777 .replace(/\n/g, '\\n')
778 .replace(/\t/g, '\\t')
779 + "');}return __p.join('');";
780 var func = new Function('obj', tmpl);
781 return data ? func(data) : func;
787 // If Underscore is called as a function, it returns a wrapped object that
788 // can be used OO-style. This wrapper holds altered versions of all the
789 // underscore functions. Wrapped objects may be chained.
790 var wrapper = function(obj) { this._wrapped = obj; };
792 // Expose `wrapper.prototype` as `_.prototype`
793 _.prototype = wrapper.prototype;
795 // Helper function to continue chaining intermediate results.
796 var result = function(obj, chain) {
797 return chain ? _(obj).chain() : obj;
800 // A method to easily add functions to the OOP wrapper.
801 var addToWrapper = function(name, func) {
802 wrapper.prototype[name] = function() {
803 var args = slice.call(arguments);
804 unshift.call(args, this._wrapped);
805 return result(func.apply(_, args), this._chain);
809 // Add all of the Underscore functions to the wrapper object.
812 // Add all mutator Array functions to the wrapper.
813 each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
814 var method = ArrayProto[name];
815 wrapper.prototype[name] = function() {
816 method.apply(this._wrapped, arguments);
817 return result(this._wrapped, this._chain);
821 // Add all accessor Array functions to the wrapper.
822 each(['concat', 'join', 'slice'], function(name) {
823 var method = ArrayProto[name];
824 wrapper.prototype[name] = function() {
825 return result(method.apply(this._wrapped, arguments), this._chain);
829 // Start chaining a wrapped Underscore object.
830 wrapper.prototype.chain = function() {
835 // Extracts the result from a wrapped and chained object.
836 wrapper.prototype.value = function() {
837 return this._wrapped;