master
1// Underscore.js 1.5.2
2// http://underscorejs.org
3// (c) 2009-2013 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
4// Underscore may be freely distributed under the MIT license.
5
6(function() {
7
8 // Baseline setup
9 // --------------
10
11 // Establish the root object, `window` in the browser, or `exports` on the server.
12 var root = this;
13
14 // Save the previous value of the `_` variable.
15 var previousUnderscore = root._;
16
17 // Establish the object that gets returned to break out of a loop iteration.
18 var breaker = {};
19
20 // Save bytes in the minified (but not gzipped) version:
21 var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;
22
23 // Create quick reference variables for speed access to core prototypes.
24 var
25 push = ArrayProto.push,
26 slice = ArrayProto.slice,
27 concat = ArrayProto.concat,
28 toString = ObjProto.toString,
29 hasOwnProperty = ObjProto.hasOwnProperty;
30
31 // All **ECMAScript 5** native function implementations that we hope to use
32 // are declared here.
33 var
34 nativeForEach = ArrayProto.forEach,
35 nativeMap = ArrayProto.map,
36 nativeReduce = ArrayProto.reduce,
37 nativeReduceRight = ArrayProto.reduceRight,
38 nativeFilter = ArrayProto.filter,
39 nativeEvery = ArrayProto.every,
40 nativeSome = ArrayProto.some,
41 nativeIndexOf = ArrayProto.indexOf,
42 nativeLastIndexOf = ArrayProto.lastIndexOf,
43 nativeIsArray = Array.isArray,
44 nativeKeys = Object.keys,
45 nativeBind = FuncProto.bind;
46
47 // Create a safe reference to the Underscore object for use below.
48 var _ = function(obj) {
49 if (obj instanceof _) return obj;
50 if (!(this instanceof _)) return new _(obj);
51 this._wrapped = obj;
52 };
53
54 // Export the Underscore object for **Node.js**, with
55 // backwards-compatibility for the old `require()` API. If we're in
56 // the browser, add `_` as a global object via a string identifier,
57 // for Closure Compiler "advanced" mode.
58 if (typeof exports !== 'undefined') {
59 if (typeof module !== 'undefined' && module.exports) {
60 exports = module.exports = _;
61 }
62 exports._ = _;
63 } else {
64 root._ = _;
65 }
66
67 // Current version.
68 _.VERSION = '1.5.2';
69
70 // Collection Functions
71 // --------------------
72
73 // The cornerstone, an `each` implementation, aka `forEach`.
74 // Handles objects with the built-in `forEach`, arrays, and raw objects.
75 // Delegates to **ECMAScript 5**'s native `forEach` if available.
76 var each = _.each = _.forEach = function(obj, iterator, context) {
77 if (obj == null) return;
78 if (nativeForEach && obj.forEach === nativeForEach) {
79 obj.forEach(iterator, context);
80 } else if (obj.length === +obj.length) {
81 for (var i = 0, length = obj.length; i < length; i++) {
82 if (iterator.call(context, obj[i], i, obj) === breaker) return;
83 }
84 } else {
85 var keys = _.keys(obj);
86 for (var i = 0, length = keys.length; i < length; i++) {
87 if (iterator.call(context, obj[keys[i]], keys[i], obj) === breaker) return;
88 }
89 }
90 };
91
92 // Return the results of applying the iterator to each element.
93 // Delegates to **ECMAScript 5**'s native `map` if available.
94 _.map = _.collect = function(obj, iterator, context) {
95 var results = [];
96 if (obj == null) return results;
97 if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
98 each(obj, function(value, index, list) {
99 results.push(iterator.call(context, value, index, list));
100 });
101 return results;
102 };
103
104 var reduceError = 'Reduce of empty array with no initial value';
105
106 // **Reduce** builds up a single result from a list of values, aka `inject`,
107 // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
108 _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
109 var initial = arguments.length > 2;
110 if (obj == null) obj = [];
111 if (nativeReduce && obj.reduce === nativeReduce) {
112 if (context) iterator = _.bind(iterator, context);
113 return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
114 }
115 each(obj, function(value, index, list) {
116 if (!initial) {
117 memo = value;
118 initial = true;
119 } else {
120 memo = iterator.call(context, memo, value, index, list);
121 }
122 });
123 if (!initial) throw new TypeError(reduceError);
124 return memo;
125 };
126
127 // The right-associative version of reduce, also known as `foldr`.
128 // Delegates to **ECMAScript 5**'s native `reduceRight` if available.
129 _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
130 var initial = arguments.length > 2;
131 if (obj == null) obj = [];
132 if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
133 if (context) iterator = _.bind(iterator, context);
134 return initial ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
135 }
136 var length = obj.length;
137 if (length !== +length) {
138 var keys = _.keys(obj);
139 length = keys.length;
140 }
141 each(obj, function(value, index, list) {
142 index = keys ? keys[--length] : --length;
143 if (!initial) {
144 memo = obj[index];
145 initial = true;
146 } else {
147 memo = iterator.call(context, memo, obj[index], index, list);
148 }
149 });
150 if (!initial) throw new TypeError(reduceError);
151 return memo;
152 };
153
154 // Return the first value which passes a truth test. Aliased as `detect`.
155 _.find = _.detect = function(obj, iterator, context) {
156 var result;
157 any(obj, function(value, index, list) {
158 if (iterator.call(context, value, index, list)) {
159 result = value;
160 return true;
161 }
162 });
163 return result;
164 };
165
166 // Return all the elements that pass a truth test.
167 // Delegates to **ECMAScript 5**'s native `filter` if available.
168 // Aliased as `select`.
169 _.filter = _.select = function(obj, iterator, context) {
170 var results = [];
171 if (obj == null) return results;
172 if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
173 each(obj, function(value, index, list) {
174 if (iterator.call(context, value, index, list)) results.push(value);
175 });
176 return results;
177 };
178
179 // Return all the elements for which a truth test fails.
180 _.reject = function(obj, iterator, context) {
181 return _.filter(obj, function(value, index, list) {
182 return !iterator.call(context, value, index, list);
183 }, context);
184 };
185
186 // Determine whether all of the elements match a truth test.
187 // Delegates to **ECMAScript 5**'s native `every` if available.
188 // Aliased as `all`.
189 _.every = _.all = function(obj, iterator, context) {
190 iterator || (iterator = _.identity);
191 var result = true;
192 if (obj == null) return result;
193 if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
194 each(obj, function(value, index, list) {
195 if (!(result = result && iterator.call(context, value, index, list))) return breaker;
196 });
197 return !!result;
198 };
199
200 // Determine if at least one element in the object matches a truth test.
201 // Delegates to **ECMAScript 5**'s native `some` if available.
202 // Aliased as `any`.
203 var any = _.some = _.any = function(obj, iterator, context) {
204 iterator || (iterator = _.identity);
205 var result = false;
206 if (obj == null) return result;
207 if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
208 each(obj, function(value, index, list) {
209 if (result || (result = iterator.call(context, value, index, list))) return breaker;
210 });
211 return !!result;
212 };
213
214 // Determine if the array or object contains a given value (using `===`).
215 // Aliased as `include`.
216 _.contains = _.include = function(obj, target) {
217 if (obj == null) return false;
218 if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
219 return any(obj, function(value) {
220 return value === target;
221 });
222 };
223
224 // Invoke a method (with arguments) on every item in a collection.
225 _.invoke = function(obj, method) {
226 var args = slice.call(arguments, 2);
227 var isFunc = _.isFunction(method);
228 return _.map(obj, function(value) {
229 return (isFunc ? method : value[method]).apply(value, args);
230 });
231 };
232
233 // Convenience version of a common use case of `map`: fetching a property.
234 _.pluck = function(obj, key) {
235 return _.map(obj, function(value){ return value[key]; });
236 };
237
238 // Convenience version of a common use case of `filter`: selecting only objects
239 // containing specific `key:value` pairs.
240 _.where = function(obj, attrs, first) {
241 if (_.isEmpty(attrs)) return first ? void 0 : [];
242 return _[first ? 'find' : 'filter'](obj, function(value) {
243 for (var key in attrs) {
244 if (attrs[key] !== value[key]) return false;
245 }
246 return true;
247 });
248 };
249
250 // Convenience version of a common use case of `find`: getting the first object
251 // containing specific `key:value` pairs.
252 _.findWhere = function(obj, attrs) {
253 return _.where(obj, attrs, true);
254 };
255
256 // Return the maximum element or (element-based computation).
257 // Can't optimize arrays of integers longer than 65,535 elements.
258 // See [WebKit Bug 80797](https://bugs.webkit.org/show_bug.cgi?id=80797)
259 _.max = function(obj, iterator, context) {
260 if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
261 return Math.max.apply(Math, obj);
262 }
263 if (!iterator && _.isEmpty(obj)) return -Infinity;
264 var result = {computed : -Infinity, value: -Infinity};
265 each(obj, function(value, index, list) {
266 var computed = iterator ? iterator.call(context, value, index, list) : value;
267 computed > result.computed && (result = {value : value, computed : computed});
268 });
269 return result.value;
270 };
271
272 // Return the minimum element (or element-based computation).
273 _.min = function(obj, iterator, context) {
274 if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
275 return Math.min.apply(Math, obj);
276 }
277 if (!iterator && _.isEmpty(obj)) return Infinity;
278 var result = {computed : Infinity, value: Infinity};
279 each(obj, function(value, index, list) {
280 var computed = iterator ? iterator.call(context, value, index, list) : value;
281 computed < result.computed && (result = {value : value, computed : computed});
282 });
283 return result.value;
284 };
285
286 // Shuffle an array, using the modern version of the
287 // [Fisher-Yates shuffle](http://en.wikipedia.org/wiki/Fisher–Yates_shuffle).
288 _.shuffle = function(obj) {
289 var rand;
290 var index = 0;
291 var shuffled = [];
292 each(obj, function(value) {
293 rand = _.random(index++);
294 shuffled[index - 1] = shuffled[rand];
295 shuffled[rand] = value;
296 });
297 return shuffled;
298 };
299
300 // Sample **n** random values from an array.
301 // If **n** is not specified, returns a single random element from the array.
302 // The internal `guard` argument allows it to work with `map`.
303 _.sample = function(obj, n, guard) {
304 if (arguments.length < 2 || guard) {
305 return obj[_.random(obj.length - 1)];
306 }
307 return _.shuffle(obj).slice(0, Math.max(0, n));
308 };
309
310 // An internal function to generate lookup iterators.
311 var lookupIterator = function(value) {
312 return _.isFunction(value) ? value : function(obj){ return obj[value]; };
313 };
314
315 // Sort the object's values by a criterion produced by an iterator.
316 _.sortBy = function(obj, value, context) {
317 var iterator = lookupIterator(value);
318 return _.pluck(_.map(obj, function(value, index, list) {
319 return {
320 value: value,
321 index: index,
322 criteria: iterator.call(context, value, index, list)
323 };
324 }).sort(function(left, right) {
325 var a = left.criteria;
326 var b = right.criteria;
327 if (a !== b) {
328 if (a > b || a === void 0) return 1;
329 if (a < b || b === void 0) return -1;
330 }
331 return left.index - right.index;
332 }), 'value');
333 };
334
335 // An internal function used for aggregate "group by" operations.
336 var group = function(behavior) {
337 return function(obj, value, context) {
338 var result = {};
339 var iterator = value == null ? _.identity : lookupIterator(value);
340 each(obj, function(value, index) {
341 var key = iterator.call(context, value, index, obj);
342 behavior(result, key, value);
343 });
344 return result;
345 };
346 };
347
348 // Groups the object's values by a criterion. Pass either a string attribute
349 // to group by, or a function that returns the criterion.
350 _.groupBy = group(function(result, key, value) {
351 (_.has(result, key) ? result[key] : (result[key] = [])).push(value);
352 });
353
354 // Indexes the object's values by a criterion, similar to `groupBy`, but for
355 // when you know that your index values will be unique.
356 _.indexBy = group(function(result, key, value) {
357 result[key] = value;
358 });
359
360 // Counts instances of an object that group by a certain criterion. Pass
361 // either a string attribute to count by, or a function that returns the
362 // criterion.
363 _.countBy = group(function(result, key) {
364 _.has(result, key) ? result[key]++ : result[key] = 1;
365 });
366
367 // Use a comparator function to figure out the smallest index at which
368 // an object should be inserted so as to maintain order. Uses binary search.
369 _.sortedIndex = function(array, obj, iterator, context) {
370 iterator = iterator == null ? _.identity : lookupIterator(iterator);
371 var value = iterator.call(context, obj);
372 var low = 0, high = array.length;
373 while (low < high) {
374 var mid = (low + high) >>> 1;
375 iterator.call(context, array[mid]) < value ? low = mid + 1 : high = mid;
376 }
377 return low;
378 };
379
380 // Safely create a real, live array from anything iterable.
381 _.toArray = function(obj) {
382 if (!obj) return [];
383 if (_.isArray(obj)) return slice.call(obj);
384 if (obj.length === +obj.length) return _.map(obj, _.identity);
385 return _.values(obj);
386 };
387
388 // Return the number of elements in an object.
389 _.size = function(obj) {
390 if (obj == null) return 0;
391 return (obj.length === +obj.length) ? obj.length : _.keys(obj).length;
392 };
393
394 // Array Functions
395 // ---------------
396
397 // Get the first element of an array. Passing **n** will return the first N
398 // values in the array. Aliased as `head` and `take`. The **guard** check
399 // allows it to work with `_.map`.
400 _.first = _.head = _.take = function(array, n, guard) {
401 if (array == null) return void 0;
402 return (n == null) || guard ? array[0] : slice.call(array, 0, n);
403 };
404
405 // Returns everything but the last entry of the array. Especially useful on
406 // the arguments object. Passing **n** will return all the values in
407 // the array, excluding the last N. The **guard** check allows it to work with
408 // `_.map`.
409 _.initial = function(array, n, guard) {
410 return slice.call(array, 0, array.length - ((n == null) || guard ? 1 : n));
411 };
412
413 // Get the last element of an array. Passing **n** will return the last N
414 // values in the array. The **guard** check allows it to work with `_.map`.
415 _.last = function(array, n, guard) {
416 if (array == null) return void 0;
417 if ((n == null) || guard) {
418 return array[array.length - 1];
419 } else {
420 return slice.call(array, Math.max(array.length - n, 0));
421 }
422 };
423
424 // Returns everything but the first entry of the array. Aliased as `tail` and `drop`.
425 // Especially useful on the arguments object. Passing an **n** will return
426 // the rest N values in the array. The **guard**
427 // check allows it to work with `_.map`.
428 _.rest = _.tail = _.drop = function(array, n, guard) {
429 return slice.call(array, (n == null) || guard ? 1 : n);
430 };
431
432 // Trim out all falsy values from an array.
433 _.compact = function(array) {
434 return _.filter(array, _.identity);
435 };
436
437 // Internal implementation of a recursive `flatten` function.
438 var flatten = function(input, shallow, output) {
439 if (shallow && _.every(input, _.isArray)) {
440 return concat.apply(output, input);
441 }
442 each(input, function(value) {
443 if (_.isArray(value) || _.isArguments(value)) {
444 shallow ? push.apply(output, value) : flatten(value, shallow, output);
445 } else {
446 output.push(value);
447 }
448 });
449 return output;
450 };
451
452 // Flatten out an array, either recursively (by default), or just one level.
453 _.flatten = function(array, shallow) {
454 return flatten(array, shallow, []);
455 };
456
457 // Return a version of the array that does not contain the specified value(s).
458 _.without = function(array) {
459 return _.difference(array, slice.call(arguments, 1));
460 };
461
462 // Produce a duplicate-free version of the array. If the array has already
463 // been sorted, you have the option of using a faster algorithm.
464 // Aliased as `unique`.
465 _.uniq = _.unique = function(array, isSorted, iterator, context) {
466 if (_.isFunction(isSorted)) {
467 context = iterator;
468 iterator = isSorted;
469 isSorted = false;
470 }
471 var initial = iterator ? _.map(array, iterator, context) : array;
472 var results = [];
473 var seen = [];
474 each(initial, function(value, index) {
475 if (isSorted ? (!index || seen[seen.length - 1] !== value) : !_.contains(seen, value)) {
476 seen.push(value);
477 results.push(array[index]);
478 }
479 });
480 return results;
481 };
482
483 // Produce an array that contains the union: each distinct element from all of
484 // the passed-in arrays.
485 _.union = function() {
486 return _.uniq(_.flatten(arguments, true));
487 };
488
489 // Produce an array that contains every item shared between all the
490 // passed-in arrays.
491 _.intersection = function(array) {
492 var rest = slice.call(arguments, 1);
493 return _.filter(_.uniq(array), function(item) {
494 return _.every(rest, function(other) {
495 return _.indexOf(other, item) >= 0;
496 });
497 });
498 };
499
500 // Take the difference between one array and a number of other arrays.
501 // Only the elements present in just the first array will remain.
502 _.difference = function(array) {
503 var rest = concat.apply(ArrayProto, slice.call(arguments, 1));
504 return _.filter(array, function(value){ return !_.contains(rest, value); });
505 };
506
507 // Zip together multiple lists into a single array -- elements that share
508 // an index go together.
509 _.zip = function() {
510 var length = _.max(_.pluck(arguments, "length").concat(0));
511 var results = new Array(length);
512 for (var i = 0; i < length; i++) {
513 results[i] = _.pluck(arguments, '' + i);
514 }
515 return results;
516 };
517
518 // Converts lists into objects. Pass either a single array of `[key, value]`
519 // pairs, or two parallel arrays of the same length -- one of keys, and one of
520 // the corresponding values.
521 _.object = function(list, values) {
522 if (list == null) return {};
523 var result = {};
524 for (var i = 0, length = list.length; i < length; i++) {
525 if (values) {
526 result[list[i]] = values[i];
527 } else {
528 result[list[i][0]] = list[i][1];
529 }
530 }
531 return result;
532 };
533
534 // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
535 // we need this function. Return the position of the first occurrence of an
536 // item in an array, or -1 if the item is not included in the array.
537 // Delegates to **ECMAScript 5**'s native `indexOf` if available.
538 // If the array is large and already in sort order, pass `true`
539 // for **isSorted** to use binary search.
540 _.indexOf = function(array, item, isSorted) {
541 if (array == null) return -1;
542 var i = 0, length = array.length;
543 if (isSorted) {
544 if (typeof isSorted == 'number') {
545 i = (isSorted < 0 ? Math.max(0, length + isSorted) : isSorted);
546 } else {
547 i = _.sortedIndex(array, item);
548 return array[i] === item ? i : -1;
549 }
550 }
551 if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
552 for (; i < length; i++) if (array[i] === item) return i;
553 return -1;
554 };
555
556 // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
557 _.lastIndexOf = function(array, item, from) {
558 if (array == null) return -1;
559 var hasIndex = from != null;
560 if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) {
561 return hasIndex ? array.lastIndexOf(item, from) : array.lastIndexOf(item);
562 }
563 var i = (hasIndex ? from : array.length);
564 while (i--) if (array[i] === item) return i;
565 return -1;
566 };
567
568 // Generate an integer Array containing an arithmetic progression. A port of
569 // the native Python `range()` function. See
570 // [the Python documentation](http://docs.python.org/library/functions.html#range).
571 _.range = function(start, stop, step) {
572 if (arguments.length <= 1) {
573 stop = start || 0;
574 start = 0;
575 }
576 step = arguments[2] || 1;
577
578 var length = Math.max(Math.ceil((stop - start) / step), 0);
579 var idx = 0;
580 var range = new Array(length);
581
582 while(idx < length) {
583 range[idx++] = start;
584 start += step;
585 }
586
587 return range;
588 };
589
590 // Function (ahem) Functions
591 // ------------------
592
593 // Reusable constructor function for prototype setting.
594 var ctor = function(){};
595
596 // Create a function bound to a given object (assigning `this`, and arguments,
597 // optionally). Delegates to **ECMAScript 5**'s native `Function.bind` if
598 // available.
599 _.bind = function(func, context) {
600 var args, bound;
601 if (nativeBind && func.bind === nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
602 if (!_.isFunction(func)) throw new TypeError;
603 args = slice.call(arguments, 2);
604 return bound = function() {
605 if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
606 ctor.prototype = func.prototype;
607 var self = new ctor;
608 ctor.prototype = null;
609 var result = func.apply(self, args.concat(slice.call(arguments)));
610 if (Object(result) === result) return result;
611 return self;
612 };
613 };
614
615 // Partially apply a function by creating a version that has had some of its
616 // arguments pre-filled, without changing its dynamic `this` context.
617 _.partial = function(func) {
618 var args = slice.call(arguments, 1);
619 return function() {
620 return func.apply(this, args.concat(slice.call(arguments)));
621 };
622 };
623
624 // Bind all of an object's methods to that object. Useful for ensuring that
625 // all callbacks defined on an object belong to it.
626 _.bindAll = function(obj) {
627 var funcs = slice.call(arguments, 1);
628 if (funcs.length === 0) throw new Error("bindAll must be passed function names");
629 each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
630 return obj;
631 };
632
633 // Memoize an expensive function by storing its results.
634 _.memoize = function(func, hasher) {
635 var memo = {};
636 hasher || (hasher = _.identity);
637 return function() {
638 var key = hasher.apply(this, arguments);
639 return _.has(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
640 };
641 };
642
643 // Delays a function for the given number of milliseconds, and then calls
644 // it with the arguments supplied.
645 _.delay = function(func, wait) {
646 var args = slice.call(arguments, 2);
647 return setTimeout(function(){ return func.apply(null, args); }, wait);
648 };
649
650 // Defers a function, scheduling it to run after the current call stack has
651 // cleared.
652 _.defer = function(func) {
653 return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
654 };
655
656 // Returns a function, that, when invoked, will only be triggered at most once
657 // during a given window of time. Normally, the throttled function will run
658 // as much as it can, without ever going more than once per `wait` duration;
659 // but if you'd like to disable the execution on the leading edge, pass
660 // `{leading: false}`. To disable execution on the trailing edge, ditto.
661 _.throttle = function(func, wait, options) {
662 var context, args, result;
663 var timeout = null;
664 var previous = 0;
665 options || (options = {});
666 var later = function() {
667 previous = options.leading === false ? 0 : new Date;
668 timeout = null;
669 result = func.apply(context, args);
670 };
671 return function() {
672 var now = new Date;
673 if (!previous && options.leading === false) previous = now;
674 var remaining = wait - (now - previous);
675 context = this;
676 args = arguments;
677 if (remaining <= 0) {
678 clearTimeout(timeout);
679 timeout = null;
680 previous = now;
681 result = func.apply(context, args);
682 } else if (!timeout && options.trailing !== false) {
683 timeout = setTimeout(later, remaining);
684 }
685 return result;
686 };
687 };
688
689 // Returns a function, that, as long as it continues to be invoked, will not
690 // be triggered. The function will be called after it stops being called for
691 // N milliseconds. If `immediate` is passed, trigger the function on the
692 // leading edge, instead of the trailing.
693 _.debounce = function(func, wait, immediate) {
694 var timeout, args, context, timestamp, result;
695 return function() {
696 context = this;
697 args = arguments;
698 timestamp = new Date();
699 var later = function() {
700 var last = (new Date()) - timestamp;
701 if (last < wait) {
702 timeout = setTimeout(later, wait - last);
703 } else {
704 timeout = null;
705 if (!immediate) result = func.apply(context, args);
706 }
707 };
708 var callNow = immediate && !timeout;
709 if (!timeout) {
710 timeout = setTimeout(later, wait);
711 }
712 if (callNow) result = func.apply(context, args);
713 return result;
714 };
715 };
716
717 // Returns a function that will be executed at most one time, no matter how
718 // often you call it. Useful for lazy initialization.
719 _.once = function(func) {
720 var ran = false, memo;
721 return function() {
722 if (ran) return memo;
723 ran = true;
724 memo = func.apply(this, arguments);
725 func = null;
726 return memo;
727 };
728 };
729
730 // Returns the first function passed as an argument to the second,
731 // allowing you to adjust arguments, run code before and after, and
732 // conditionally execute the original function.
733 _.wrap = function(func, wrapper) {
734 return function() {
735 var args = [func];
736 push.apply(args, arguments);
737 return wrapper.apply(this, args);
738 };
739 };
740
741 // Returns a function that is the composition of a list of functions, each
742 // consuming the return value of the function that follows.
743 _.compose = function() {
744 var funcs = arguments;
745 return function() {
746 var args = arguments;
747 for (var i = funcs.length - 1; i >= 0; i--) {
748 args = [funcs[i].apply(this, args)];
749 }
750 return args[0];
751 };
752 };
753
754 // Returns a function that will only be executed after being called N times.
755 _.after = function(times, func) {
756 return function() {
757 if (--times < 1) {
758 return func.apply(this, arguments);
759 }
760 };
761 };
762
763 // Object Functions
764 // ----------------
765
766 // Retrieve the names of an object's properties.
767 // Delegates to **ECMAScript 5**'s native `Object.keys`
768 _.keys = nativeKeys || function(obj) {
769 if (obj !== Object(obj)) throw new TypeError('Invalid object');
770 var keys = [];
771 for (var key in obj) if (_.has(obj, key)) keys.push(key);
772 return keys;
773 };
774
775 // Retrieve the values of an object's properties.
776 _.values = function(obj) {
777 var keys = _.keys(obj);
778 var length = keys.length;
779 var values = new Array(length);
780 for (var i = 0; i < length; i++) {
781 values[i] = obj[keys[i]];
782 }
783 return values;
784 };
785
786 // Convert an object into a list of `[key, value]` pairs.
787 _.pairs = function(obj) {
788 var keys = _.keys(obj);
789 var length = keys.length;
790 var pairs = new Array(length);
791 for (var i = 0; i < length; i++) {
792 pairs[i] = [keys[i], obj[keys[i]]];
793 }
794 return pairs;
795 };
796
797 // Invert the keys and values of an object. The values must be serializable.
798 _.invert = function(obj) {
799 var result = {};
800 var keys = _.keys(obj);
801 for (var i = 0, length = keys.length; i < length; i++) {
802 result[obj[keys[i]]] = keys[i];
803 }
804 return result;
805 };
806
807 // Return a sorted list of the function names available on the object.
808 // Aliased as `methods`
809 _.functions = _.methods = function(obj) {
810 var names = [];
811 for (var key in obj) {
812 if (_.isFunction(obj[key])) names.push(key);
813 }
814 return names.sort();
815 };
816
817 // Extend a given object with all the properties in passed-in object(s).
818 _.extend = function(obj) {
819 each(slice.call(arguments, 1), function(source) {
820 if (source) {
821 for (var prop in source) {
822 obj[prop] = source[prop];
823 }
824 }
825 });
826 return obj;
827 };
828
829 // Return a copy of the object only containing the whitelisted properties.
830 _.pick = function(obj) {
831 var copy = {};
832 var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
833 each(keys, function(key) {
834 if (key in obj) copy[key] = obj[key];
835 });
836 return copy;
837 };
838
839 // Return a copy of the object without the blacklisted properties.
840 _.omit = function(obj) {
841 var copy = {};
842 var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
843 for (var key in obj) {
844 if (!_.contains(keys, key)) copy[key] = obj[key];
845 }
846 return copy;
847 };
848
849 // Fill in a given object with default properties.
850 _.defaults = function(obj) {
851 each(slice.call(arguments, 1), function(source) {
852 if (source) {
853 for (var prop in source) {
854 if (obj[prop] === void 0) obj[prop] = source[prop];
855 }
856 }
857 });
858 return obj;
859 };
860
861 // Create a (shallow-cloned) duplicate of an object.
862 _.clone = function(obj) {
863 if (!_.isObject(obj)) return obj;
864 return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
865 };
866
867 // Invokes interceptor with the obj, and then returns obj.
868 // The primary purpose of this method is to "tap into" a method chain, in
869 // order to perform operations on intermediate results within the chain.
870 _.tap = function(obj, interceptor) {
871 interceptor(obj);
872 return obj;
873 };
874
875 // Internal recursive comparison function for `isEqual`.
876 var eq = function(a, b, aStack, bStack) {
877 // Identical objects are equal. `0 === -0`, but they aren't identical.
878 // See the [Harmony `egal` proposal](http://wiki.ecmascript.org/doku.php?id=harmony:egal).
879 if (a === b) return a !== 0 || 1 / a == 1 / b;
880 // A strict comparison is necessary because `null == undefined`.
881 if (a == null || b == null) return a === b;
882 // Unwrap any wrapped objects.
883 if (a instanceof _) a = a._wrapped;
884 if (b instanceof _) b = b._wrapped;
885 // Compare `[[Class]]` names.
886 var className = toString.call(a);
887 if (className != toString.call(b)) return false;
888 switch (className) {
889 // Strings, numbers, dates, and booleans are compared by value.
890 case '[object String]':
891 // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
892 // equivalent to `new String("5")`.
893 return a == String(b);
894 case '[object Number]':
895 // `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for
896 // other numeric values.
897 return a != +a ? b != +b : (a == 0 ? 1 / a == 1 / b : a == +b);
898 case '[object Date]':
899 case '[object Boolean]':
900 // Coerce dates and booleans to numeric primitive values. Dates are compared by their
901 // millisecond representations. Note that invalid dates with millisecond representations
902 // of `NaN` are not equivalent.
903 return +a == +b;
904 // RegExps are compared by their source patterns and flags.
905 case '[object RegExp]':
906 return a.source == b.source &&
907 a.global == b.global &&
908 a.multiline == b.multiline &&
909 a.ignoreCase == b.ignoreCase;
910 }
911 if (typeof a != 'object' || typeof b != 'object') return false;
912 // Assume equality for cyclic structures. The algorithm for detecting cyclic
913 // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
914 var length = aStack.length;
915 while (length--) {
916 // Linear search. Performance is inversely proportional to the number of
917 // unique nested structures.
918 if (aStack[length] == a) return bStack[length] == b;
919 }
920 // Objects with different constructors are not equivalent, but `Object`s
921 // from different frames are.
922 var aCtor = a.constructor, bCtor = b.constructor;
923 if (aCtor !== bCtor && !(_.isFunction(aCtor) && (aCtor instanceof aCtor) &&
924 _.isFunction(bCtor) && (bCtor instanceof bCtor))) {
925 return false;
926 }
927 // Add the first object to the stack of traversed objects.
928 aStack.push(a);
929 bStack.push(b);
930 var size = 0, result = true;
931 // Recursively compare objects and arrays.
932 if (className == '[object Array]') {
933 // Compare array lengths to determine if a deep comparison is necessary.
934 size = a.length;
935 result = size == b.length;
936 if (result) {
937 // Deep compare the contents, ignoring non-numeric properties.
938 while (size--) {
939 if (!(result = eq(a[size], b[size], aStack, bStack))) break;
940 }
941 }
942 } else {
943 // Deep compare objects.
944 for (var key in a) {
945 if (_.has(a, key)) {
946 // Count the expected number of properties.
947 size++;
948 // Deep compare each member.
949 if (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) break;
950 }
951 }
952 // Ensure that both objects contain the same number of properties.
953 if (result) {
954 for (key in b) {
955 if (_.has(b, key) && !(size--)) break;
956 }
957 result = !size;
958 }
959 }
960 // Remove the first object from the stack of traversed objects.
961 aStack.pop();
962 bStack.pop();
963 return result;
964 };
965
966 // Perform a deep comparison to check if two objects are equal.
967 _.isEqual = function(a, b) {
968 return eq(a, b, [], []);
969 };
970
971 // Is a given array, string, or object empty?
972 // An "empty" object has no enumerable own-properties.
973 _.isEmpty = function(obj) {
974 if (obj == null) return true;
975 if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
976 for (var key in obj) if (_.has(obj, key)) return false;
977 return true;
978 };
979
980 // Is a given value a DOM element?
981 _.isElement = function(obj) {
982 return !!(obj && obj.nodeType === 1);
983 };
984
985 // Is a given value an array?
986 // Delegates to ECMA5's native Array.isArray
987 _.isArray = nativeIsArray || function(obj) {
988 return toString.call(obj) == '[object Array]';
989 };
990
991 // Is a given variable an object?
992 _.isObject = function(obj) {
993 return obj === Object(obj);
994 };
995
996 // Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp.
997 each(['Arguments', 'Function', 'String', 'Number', 'Date', 'RegExp'], function(name) {
998 _['is' + name] = function(obj) {
999 return toString.call(obj) == '[object ' + name + ']';
1000 };
1001 });
1002
1003 // Define a fallback version of the method in browsers (ahem, IE), where
1004 // there isn't any inspectable "Arguments" type.
1005 if (!_.isArguments(arguments)) {
1006 _.isArguments = function(obj) {
1007 return !!(obj && _.has(obj, 'callee'));
1008 };
1009 }
1010
1011 // Optimize `isFunction` if appropriate.
1012 if (typeof (/./) !== 'function') {
1013 _.isFunction = function(obj) {
1014 return typeof obj === 'function';
1015 };
1016 }
1017
1018 // Is a given object a finite number?
1019 _.isFinite = function(obj) {
1020 return isFinite(obj) && !isNaN(parseFloat(obj));
1021 };
1022
1023 // Is the given value `NaN`? (NaN is the only number which does not equal itself).
1024 _.isNaN = function(obj) {
1025 return _.isNumber(obj) && obj != +obj;
1026 };
1027
1028 // Is a given value a boolean?
1029 _.isBoolean = function(obj) {
1030 return obj === true || obj === false || toString.call(obj) == '[object Boolean]';
1031 };
1032
1033 // Is a given value equal to null?
1034 _.isNull = function(obj) {
1035 return obj === null;
1036 };
1037
1038 // Is a given variable undefined?
1039 _.isUndefined = function(obj) {
1040 return obj === void 0;
1041 };
1042
1043 // Shortcut function for checking if an object has a given property directly
1044 // on itself (in other words, not on a prototype).
1045 _.has = function(obj, key) {
1046 return hasOwnProperty.call(obj, key);
1047 };
1048
1049 // Utility Functions
1050 // -----------------
1051
1052 // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
1053 // previous owner. Returns a reference to the Underscore object.
1054 _.noConflict = function() {
1055 root._ = previousUnderscore;
1056 return this;
1057 };
1058
1059 // Keep the identity function around for default iterators.
1060 _.identity = function(value) {
1061 return value;
1062 };
1063
1064 // Run a function **n** times.
1065 _.times = function(n, iterator, context) {
1066 var accum = Array(Math.max(0, n));
1067 for (var i = 0; i < n; i++) accum[i] = iterator.call(context, i);
1068 return accum;
1069 };
1070
1071 // Return a random integer between min and max (inclusive).
1072 _.random = function(min, max) {
1073 if (max == null) {
1074 max = min;
1075 min = 0;
1076 }
1077 return min + Math.floor(Math.random() * (max - min + 1));
1078 };
1079
1080 // List of HTML entities for escaping.
1081 var entityMap = {
1082 escape: {
1083 '&': '&',
1084 '<': '<',
1085 '>': '>',
1086 '"': '"',
1087 "'": '''
1088 }
1089 };
1090 entityMap.unescape = _.invert(entityMap.escape);
1091
1092 // Regexes containing the keys and values listed immediately above.
1093 var entityRegexes = {
1094 escape: new RegExp('[' + _.keys(entityMap.escape).join('') + ']', 'g'),
1095 unescape: new RegExp('(' + _.keys(entityMap.unescape).join('|') + ')', 'g')
1096 };
1097
1098 // Functions for escaping and unescaping strings to/from HTML interpolation.
1099 _.each(['escape', 'unescape'], function(method) {
1100 _[method] = function(string) {
1101 if (string == null) return '';
1102 return ('' + string).replace(entityRegexes[method], function(match) {
1103 return entityMap[method][match];
1104 });
1105 };
1106 });
1107
1108 // If the value of the named `property` is a function then invoke it with the
1109 // `object` as context; otherwise, return it.
1110 _.result = function(object, property) {
1111 if (object == null) return void 0;
1112 var value = object[property];
1113 return _.isFunction(value) ? value.call(object) : value;
1114 };
1115
1116 // Add your own custom functions to the Underscore object.
1117 _.mixin = function(obj) {
1118 each(_.functions(obj), function(name) {
1119 var func = _[name] = obj[name];
1120 _.prototype[name] = function() {
1121 var args = [this._wrapped];
1122 push.apply(args, arguments);
1123 return result.call(this, func.apply(_, args));
1124 };
1125 });
1126 };
1127
1128 // Generate a unique integer id (unique within the entire client session).
1129 // Useful for temporary DOM ids.
1130 var idCounter = 0;
1131 _.uniqueId = function(prefix) {
1132 var id = ++idCounter + '';
1133 return prefix ? prefix + id : id;
1134 };
1135
1136 // By default, Underscore uses ERB-style template delimiters, change the
1137 // following template settings to use alternative delimiters.
1138 _.templateSettings = {
1139 evaluate : /<%([\s\S]+?)%>/g,
1140 interpolate : /<%=([\s\S]+?)%>/g,
1141 escape : /<%-([\s\S]+?)%>/g
1142 };
1143
1144 // When customizing `templateSettings`, if you don't want to define an
1145 // interpolation, evaluation or escaping regex, we need one that is
1146 // guaranteed not to match.
1147 var noMatch = /(.)^/;
1148
1149 // Certain characters need to be escaped so that they can be put into a
1150 // string literal.
1151 var escapes = {
1152 "'": "'",
1153 '\\': '\\',
1154 '\r': 'r',
1155 '\n': 'n',
1156 '\t': 't',
1157 '\u2028': 'u2028',
1158 '\u2029': 'u2029'
1159 };
1160
1161 var escaper = /\\|'|\r|\n|\t|\u2028|\u2029/g;
1162
1163 // JavaScript micro-templating, similar to John Resig's implementation.
1164 // Underscore templating handles arbitrary delimiters, preserves whitespace,
1165 // and correctly escapes quotes within interpolated code.
1166 _.template = function(text, data, settings) {
1167 var render;
1168 settings = _.defaults({}, settings, _.templateSettings);
1169
1170 // Combine delimiters into one regular expression via alternation.
1171 var matcher = new RegExp([
1172 (settings.escape || noMatch).source,
1173 (settings.interpolate || noMatch).source,
1174 (settings.evaluate || noMatch).source
1175 ].join('|') + '|$', 'g');
1176
1177 // Compile the template source, escaping string literals appropriately.
1178 var index = 0;
1179 var source = "__p+='";
1180 text.replace(matcher, function(match, escape, interpolate, evaluate, offset) {
1181 source += text.slice(index, offset)
1182 .replace(escaper, function(match) { return '\\' + escapes[match]; });
1183
1184 if (escape) {
1185 source += "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'";
1186 }
1187 if (interpolate) {
1188 source += "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'";
1189 }
1190 if (evaluate) {
1191 source += "';\n" + evaluate + "\n__p+='";
1192 }
1193 index = offset + match.length;
1194 return match;
1195 });
1196 source += "';\n";
1197
1198 // If a variable is not specified, place data values in local scope.
1199 if (!settings.variable) source = 'with(obj||{}){\n' + source + '}\n';
1200
1201 source = "var __t,__p='',__j=Array.prototype.join," +
1202 "print=function(){__p+=__j.call(arguments,'');};\n" +
1203 source + "return __p;\n";
1204
1205 try {
1206 render = new Function(settings.variable || 'obj', '_', source);
1207 } catch (e) {
1208 e.source = source;
1209 throw e;
1210 }
1211
1212 if (data) return render(data, _);
1213 var template = function(data) {
1214 return render.call(this, data, _);
1215 };
1216
1217 // Provide the compiled function source as a convenience for precompilation.
1218 template.source = 'function(' + (settings.variable || 'obj') + '){\n' + source + '}';
1219
1220 return template;
1221 };
1222
1223 // Add a "chain" function, which will delegate to the wrapper.
1224 _.chain = function(obj) {
1225 return _(obj).chain();
1226 };
1227
1228 // OOP
1229 // ---------------
1230 // If Underscore is called as a function, it returns a wrapped object that
1231 // can be used OO-style. This wrapper holds altered versions of all the
1232 // underscore functions. Wrapped objects may be chained.
1233
1234 // Helper function to continue chaining intermediate results.
1235 var result = function(obj) {
1236 return this._chain ? _(obj).chain() : obj;
1237 };
1238
1239 // Add all of the Underscore functions to the wrapper object.
1240 _.mixin(_);
1241
1242 // Add all mutator Array functions to the wrapper.
1243 each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
1244 var method = ArrayProto[name];
1245 _.prototype[name] = function() {
1246 var obj = this._wrapped;
1247 method.apply(obj, arguments);
1248 if ((name == 'shift' || name == 'splice') && obj.length === 0) delete obj[0];
1249 return result.call(this, obj);
1250 };
1251 });
1252
1253 // Add all accessor Array functions to the wrapper.
1254 each(['concat', 'join', 'slice'], function(name) {
1255 var method = ArrayProto[name];
1256 _.prototype[name] = function() {
1257 return result.call(this, method.apply(this._wrapped, arguments));
1258 };
1259 });
1260
1261 _.extend(_.prototype, {
1262
1263 // Start chaining a wrapped Underscore object.
1264 chain: function() {
1265 this._chain = true;
1266 return this;
1267 },
1268
1269 // Extracts the result from a wrapped and chained object.
1270 value: function() {
1271 return this._wrapped;
1272 }
1273
1274 });
1275
1276}).call(this);