(function() {Underscore.js 1.7.0
http://underscorejs.org
(c) 2009-2014 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
Underscore may be freely distributed under the MIT license.
(function() {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._;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
nativeIsArray = Array.isArray,
nativeKeys = Object.keys,
nativeBind = FuncProto.bind;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.
if (typeof exports !== 'undefined') {
if (typeof module !== 'undefined' && module.exports) {
exports = module.exports = _;
}
exports._ = _;
} else {
root._ = _;
}Current version.
_.VERSION = '1.7.0';Internal function that returns an efficient (for current engines) version of the passed-in callback, to be repeatedly applied in other Underscore functions.
var createCallback = 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.
_.iteratee = function(value, context, argCount) {
if (value == null) return _.identity;
if (_.isFunction(value)) return createCallback(value, context, argCount);
if (_.isObject(value)) return _.matches(value);
return _.property(value);
};The cornerstone, an each implementation, aka forEach.
Handles raw objects in addition to array-likes. Treats all
sparse array-likes as if they were dense.
_.each = _.forEach = function(obj, iteratee, context) {
if (obj == null) return obj;
iteratee = createCallback(iteratee, context);
var i, length = obj.length;
if (length === +length) {
for (i = 0; i < length; i++) {
iteratee(obj[i], i, obj);
}
} else {
var keys = _.keys(obj);
for (i = 0, length = keys.length; i < length; i++) {
iteratee(obj[keys[i]], keys[i], obj);
}
}
return obj;
};Return the results of applying the iteratee to each element.
_.map = _.collect = function(obj, iteratee, context) {
if (obj == null) return [];
iteratee = _.iteratee(iteratee, context);
var keys = obj.length !== +obj.length && _.keys(obj),
length = (keys || obj).length,
results = Array(length),
currentKey;
for (var index = 0; index < length; index++) {
currentKey = keys ? keys[index] : index;
results[index] = iteratee(obj[currentKey], currentKey, obj);
}
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.
_.reduce = _.foldl = _.inject = function(obj, iteratee, memo, context) {
if (obj == null) obj = [];
iteratee = createCallback(iteratee, context, 4);
var keys = obj.length !== +obj.length && _.keys(obj),
length = (keys || obj).length,
index = 0, currentKey;
if (arguments.length < 3) {
if (!length) throw new TypeError(reduceError);
memo = obj[keys ? keys[index++] : index++];
}
for (; index < length; index++) {
currentKey = keys ? keys[index] : index;
memo = iteratee(memo, obj[currentKey], currentKey, obj);
}
return memo;
};The right-associative version of reduce, also known as foldr.
_.reduceRight = _.foldr = function(obj, iteratee, memo, context) {
if (obj == null) obj = [];
iteratee = createCallback(iteratee, context, 4);
var keys = obj.length !== + obj.length && _.keys(obj),
index = (keys || obj).length,
currentKey;
if (arguments.length < 3) {
if (!index) throw new TypeError(reduceError);
memo = obj[keys ? keys[--index] : --index];
}
while (index--) {
currentKey = keys ? keys[index] : index;
memo = iteratee(memo, obj[currentKey], currentKey, obj);
}
return memo;
};Return the first value which passes a truth test. Aliased as detect.
_.find = _.detect = function(obj, predicate, context) {
var result;
predicate = _.iteratee(predicate, context);
_.some(obj, function(value, index, list) {
if (predicate(value, index, list)) {
result = value;
return true;
}
});
return result;
};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 = _.iteratee(predicate, context);
_.each(obj, function(value, index, list) {
if (predicate(value, index, list)) results.push(value);
});
return results;
};Return all the elements for which a truth test fails.
_.reject = function(obj, predicate, context) {
return _.filter(obj, _.negate(_.iteratee(predicate)), context);
};Determine whether all of the elements match a truth test.
Aliased as all.
_.every = _.all = function(obj, predicate, context) {
if (obj == null) return true;
predicate = _.iteratee(predicate, context);
var keys = obj.length !== +obj.length && _.keys(obj),
length = (keys || obj).length,
index, currentKey;
for (index = 0; index < length; index++) {
currentKey = keys ? keys[index] : index;
if (!predicate(obj[currentKey], currentKey, obj)) return false;
}
return true;
};Determine if at least one element in the object matches a truth test.
Aliased as any.
_.some = _.any = function(obj, predicate, context) {
if (obj == null) return false;
predicate = _.iteratee(predicate, context);
var keys = obj.length !== +obj.length && _.keys(obj),
length = (keys || obj).length,
index, currentKey;
for (index = 0; index < length; index++) {
currentKey = keys ? keys[index] : index;
if (predicate(obj[currentKey], currentKey, obj)) return true;
}
return false;
};Determine if the array or object contains a given value (using ===).
Aliased as include.
_.contains = _.include = function(obj, target) {
if (obj == null) return false;
if (obj.length !== +obj.length) obj = _.values(obj);
return _.indexOf(obj, target) >= 0;
};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);
});
};Convenience version of a common use case of map: fetching a property.
_.pluck = function(obj, 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) {
return _.filter(obj, _.matches(attrs));
};Convenience version of a common use case of find: getting the first object
containing specific key:value pairs.
_.findWhere = function(obj, attrs) {
return _.find(obj, _.matches(attrs));
};Return the maximum element (or element-based computation).
_.max = function(obj, iteratee, context) {
var result = -Infinity, lastComputed = -Infinity,
value, computed;
if (iteratee == null && obj != null) {
obj = obj.length === +obj.length ? obj : _.values(obj);
for (var i = 0, length = obj.length; i < length; i++) {
value = obj[i];
if (value > result) {
result = value;
}
}
} else {
iteratee = _.iteratee(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, iteratee, context) {
var result = Infinity, lastComputed = Infinity,
value, computed;
if (iteratee == null && obj != null) {
obj = obj.length === +obj.length ? obj : _.values(obj);
for (var i = 0, length = obj.length; i < length; i++) {
value = obj[i];
if (value < result) {
result = value;
}
}
} else {
iteratee = _.iteratee(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;
};Shuffle a collection, using the modern version of the Fisher-Yates shuffle.
_.shuffle = function(obj) {
var set = obj && obj.length === +obj.length ? obj : _.values(obj);
var length = set.length;
var shuffled = Array(length);
for (var index = 0, rand; index < length; index++) {
rand = _.random(0, index);
if (rand !== index) shuffled[index] = shuffled[rand];
shuffled[rand] = set[index];
}
return shuffled;
};Sample n random values from a collection.
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 (n == null || guard) {
if (obj.length !== +obj.length) obj = _.values(obj);
return obj[_.random(obj.length - 1)];
}
return _.shuffle(obj).slice(0, Math.max(0, n));
};Sort the object’s values by a criterion produced by an iteratee.
_.sortBy = function(obj, iteratee, context) {
iteratee = _.iteratee(iteratee, context);
return _.pluck(_.map(obj, function(value, index, list) {
return {
value: value,
index: index,
criteria: iteratee(value, index, list)
};
}).sort(function(left, right) {
var a = left.criteria;
var b = right.criteria;
if (a !== b) {
if (a > b || a === void 0) return 1;
if (a < b || b === void 0) return -1;
}
return left.index - right.index;
}), 'value');
};An internal function used for aggregate “group by” operations.
var group = function(behavior) {
return function(obj, iteratee, context) {
var result = {};
iteratee = _.iteratee(iteratee, context);
_.each(obj, function(value, index) {
var key = iteratee(value, index, obj);
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, value, key) {
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, 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, value, key) {
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, iteratee, context) {
iteratee = _.iteratee(iteratee, context, 1);
var value = iteratee(obj);
var low = 0, high = array.length;
while (low < high) {
var mid = low + high >>> 1;
if (iteratee(array[mid]) < value) low = mid + 1; else 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);
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;
};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 = _.iteratee(predicate, context);
var pass = [], fail = [];
_.each(obj, function(value, key, obj) {
(predicate(value, key, obj) ? pass : fail).push(value);
});
return [pass, fail];
};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;
if (n == null || guard) return array[0];
if (n < 0) return [];
return slice.call(array, 0, 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
_.map.
_.initial = function(array, n, guard) {
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.
_.last = function(array, n, guard) {
if (array == null) return void 0;
if (n == null || guard) return array[array.length - 1];
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
check allows it to work with _.map.
_.rest = _.tail = _.drop = function(array, n, guard) {
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, strict, output) {
if (shallow && _.every(input, _.isArray)) {
return concat.apply(output, input);
}
for (var i = 0, length = input.length; i < length; i++) {
var value = input[i];
if (!_.isArray(value) && !_.isArguments(value)) {
if (!strict) output.push(value);
} else if (shallow) {
push.apply(output, value);
} else {
flatten(value, shallow, strict, output);
}
}
return output;
};Flatten out an array, either recursively (by default), or just one level.
_.flatten = function(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, iteratee, context) {
if (array == null) return [];
if (!_.isBoolean(isSorted)) {
context = iteratee;
iteratee = isSorted;
isSorted = false;
}
if (iteratee != null) iteratee = _.iteratee(iteratee, context);
var result = [];
var seen = [];
for (var i = 0, length = array.length; i < length; i++) {
var value = array[i];
if (isSorted) {
if (!i || seen !== value) result.push(value);
seen = value;
} else if (iteratee) {
var computed = iteratee(value, i, array);
if (_.indexOf(seen, computed) < 0) {
seen.push(computed);
result.push(value);
}
} else if (_.indexOf(result, value) < 0) {
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, true, []));
};Produce an array that contains every item shared between all the passed-in arrays.
_.intersection = function(array) {
if (array == null) return [];
var result = [];
var argsLength = arguments.length;
for (var i = 0, length = array.length; i < length; i++) {
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 = flatten(slice.call(arguments, 1), true, true, []);
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(array) {
if (array == null) return [];
var length = _.max(arguments, 'length').length;
var results = Array(length);
for (var i = 0; i < length; i++) {
results[i] = _.pluck(arguments, i);
}
return results;
};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++) {
if (values) {
result[list[i]] = values[i];
} else {
result[list[i][0]] = list[i][1];
}
}
return result;
};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) {
if (array == null) return -1;
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;
}
}
for (; i < length; i++) if (array[i] === item) return i;
return -1;
};
_.lastIndexOf = function(array, item, from) {
if (array == null) return -1;
var idx = array.length;
if (typeof from == 'number') {
idx = from < 0 ? idx + from + 1 : Math.min(idx, from + 1);
}
while (--idx >= 0) if (array[idx] === item) return idx;
return -1;
};Generate an integer Array containing an arithmetic progression. A port of
the native Python range() function. See
the Python documentation.
_.range = function(start, stop, step) {
if (arguments.length <= 1) {
stop = start || 0;
start = 0;
}
step = step || 1;
var length = Math.max(Math.ceil((stop - start) / step), 0);
var range = Array(length);
for (var idx = 0; idx < length; idx++, start += step) {
range[idx] = start;
}
return range;
};Reusable constructor function for prototype setting.
var Ctor = function(){};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('Bind must be called on a function');
args = slice.call(arguments, 2);
bound = function() {
if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
Ctor.prototype = func.prototype;
var self = new Ctor;
Ctor.prototype = null;
var result = func.apply(self, args.concat(slice.call(arguments)));
if (_.isObject(result)) return result;
return self;
};
return bound;
};Partially apply a function by creating a version that has had some of its
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 boundArgs = slice.call(arguments, 1);
return function() {
var position = 0;
var args = boundArgs.slice();
for (var i = 0, length = args.length; i < length; i++) {
if (args[i] === _) args[i] = arguments[position++];
}
while (position < arguments.length) args.push(arguments[position++]);
return func.apply(this, args);
};
};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 i, length = arguments.length, key;
if (length <= 1) throw new Error('bindAll must be passed function names');
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 memoize = function(key) {
var cache = memoize.cache;
var address = hasher ? hasher.apply(this, arguments) : key;
if (!_.has(cache, address)) cache[address] = 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);
};Defers a function, scheduling it to run after the current call stack has cleared.
_.defer = function(func) {
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;
if (!options) options = {};
var later = function() {
previous = options.leading === false ? 0 : _.now();
timeout = null;
result = func.apply(context, args);
if (!timeout) context = args = null;
};
return function() {
var now = _.now();
if (!previous && options.leading === false) previous = now;
var remaining = wait - (now - previous);
context = this;
args = arguments;
if (remaining <= 0 || remaining > wait) {
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;
};
};Returns a function, that, as long as it continues to be invoked, will not
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 = _.now();
var callNow = immediate && !timeout;
if (!timeout) timeout = setTimeout(later, wait);
if (callNow) {
result = func.apply(context, args);
context = args = null;
}
return result;
};
};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() {
return !predicate.apply(this, arguments);
};
};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 args = arguments;
var start = args.length - 1;
return function() {
var i = start;
var result = args[start].apply(this, arguments);
while (i--) result = args[i].call(this, result);
return result;
};
};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 before being called N times.
_.before = function(times, func) {
var memo;
return function() {
if (--times > 0) {
memo = func.apply(this, arguments);
} else {
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);Retrieve the names of an object’s properties.
Delegates to ECMAScript 5‘s native Object.keys
_.keys = function(obj) {
if (!_.isObject(obj)) return [];
if (nativeKeys) return nativeKeys(obj);
var keys = [];
for (var key in obj) if (_.has(obj, key)) keys.push(key);
return keys;
};Retrieve the values of an object’s properties.
_.values = function(obj) {
var keys = _.keys(obj);
var length = keys.length;
var values = Array(length);
for (var i = 0; i < length; i++) {
values[i] = obj[keys[i]];
}
return values;
};Convert an object into a list of [key, value] pairs.
_.pairs = function(obj) {
var keys = _.keys(obj);
var length = keys.length;
var pairs = Array(length);
for (var i = 0; i < length; i++) {
pairs[i] = [keys[i], obj[keys[i]]];
}
return pairs;
};Invert the keys and values of an object. The values must be serializable.
_.invert = function(obj) {
var result = {};
var keys = _.keys(obj);
for (var i = 0, length = keys.length; i < length; i++) {
result[obj[keys[i]]] = keys[i];
}
return result;
};Return a sorted list of the function names available on the object.
Aliased as methods
_.functions = _.methods = function(obj) {
var names = [];
for (var key in obj) {
if (_.isFunction(obj[key])) names.push(key);
}
return names.sort();
};Extend a given object with all the properties in passed-in object(s).
_.extend = function(obj) {
if (!_.isObject(obj)) return obj;
var source, prop;
for (var i = 1, length = arguments.length; i < length; i++) {
source = arguments[i];
for (prop in source) {
if (hasOwnProperty.call(source, prop)) {
obj[prop] = source[prop];
}
}
}
return obj;
};Return a copy of the object only containing the whitelisted properties.
_.pick = function(obj, iteratee, context) {
var result = {}, key;
if (obj == null) return result;
if (_.isFunction(iteratee)) {
iteratee = createCallback(iteratee, context);
for (key in obj) {
var value = obj[key];
if (iteratee(value, key, obj)) result[key] = value;
}
} else {
var keys = concat.apply([], slice.call(arguments, 1));
obj = new Object(obj);
for (var i = 0, length = keys.length; i < length; i++) {
key = keys[i];
if (key in obj) result[key] = obj[key];
}
}
return result;
};Return a copy of the object without the blacklisted properties.
_.omit = function(obj, iteratee, context) {
if (_.isFunction(iteratee)) {
iteratee = _.negate(iteratee);
} else {
var keys = _.map(concat.apply([], slice.call(arguments, 1)), String);
iteratee = function(value, key) {
return !_.contains(keys, key);
};
}
return _.pick(obj, iteratee, context);
};Fill in a given object with default properties.
_.defaults = function(obj) {
if (!_.isObject(obj)) return obj;
for (var i = 1, length = arguments.length; i < length; i++) {
var source = arguments[i];
for (var prop in source) {
if (obj[prop] === void 0) obj[prop] = source[prop];
}
}
return obj;
};Create a (shallow-cloned) duplicate of an object.
_.clone = function(obj) {
if (!_.isObject(obj)) return obj;
return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
};Invokes interceptor with the obj, and then returns obj. The primary purpose of this method is to “tap into” a method chain, in order to perform operations on intermediate results within the chain.
_.tap = function(obj, interceptor) {
interceptor(obj);
return obj;
};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.
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;
switch (className) {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 === '' + b;
case '[object Number]':NaNs are equivalent, but non-reflexive.
Object(NaN) is equivalent to NaN
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;
}
if (typeof a != 'object' || typeof b != 'object') 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.
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;
}Objects with different constructors are not equivalent, but Objects
from different frames are.
var aCtor = a.constructor, bCtor = b.constructor;
if (
aCtor !== bCtor &&Handle Object.create(x) cases
'constructor' in a && 'constructor' in b &&
!(_.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, result;Recursively compare objects and arrays.
if (className === '[object Array]') {Compare array lengths to determine if a deep comparison is necessary.
size = a.length;
result = size === b.length;
if (result) {Deep compare the contents, ignoring non-numeric properties.
while (size--) {
if (!(result = eq(a[size], b[size], aStack, bStack))) break;
}
}
} else {Deep compare objects.
var keys = _.keys(a), key;
size = keys.length;Ensure that both objects contain the same number of properties before comparing deep equality.
result = _.keys(b).length === size;
if (result) {
while (size--) {Deep compare each member
key = keys[size];
if (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) break;
}
}
}Remove the first object from the stack of traversed objects.
aStack.pop();
bStack.pop();
return result;
};Perform a deep comparison to check if two objects are equal.
_.isEqual = function(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) || _.isArguments(obj)) return obj.length === 0;
for (var key in obj) if (_.has(obj, key)) return false;
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]';
};Is a given variable an object?
_.isObject = function(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) {
_['is' + name] = function(obj) {
return toString.call(obj) === '[object ' + name + ']';
};
});Define a fallback version of the method in browsers (ahem, IE), where there isn’t any inspectable “Arguments” type.
if (!_.isArguments(arguments)) {
_.isArguments = function(obj) {
return _.has(obj, 'callee');
};
}Optimize isFunction if appropriate. Work around an IE 11 bug.
if (typeof /./ !== 'function') {
_.isFunction = function(obj) {
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;
};Is a given value a boolean?
_.isBoolean = function(obj) {
return obj === true || obj === false || toString.call(obj) === '[object Boolean]';
};Is a given value equal to null?
_.isNull = function(obj) {
return obj === null;
};Is a given variable undefined?
_.isUndefined = function(obj) {
return obj === void 0;
};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 obj != null && hasOwnProperty.call(obj, key);
};Run Underscore.js in noConflict mode, returning the _ variable to its
previous owner. Returns a reference to the Underscore object.
_.noConflict = function() {
root._ = previousUnderscore;
return this;
};Keep the identity function around for default iteratees.
_.identity = function(value) {
return value;
};
_.constant = function(value) {
return function() {
return value;
};
};
_.noop = function(){};
_.property = function(key) {
return function(obj) {
return obj[key];
};
};Returns a predicate for checking whether an object has a given set of key:value pairs.
_.matches = function(attrs) {
var pairs = _.pairs(attrs), length = pairs.length;
return function(obj) {
if (obj == null) return !length;
obj = new Object(obj);
for (var i = 0; i < length; i++) {
var pair = pairs[i], key = pair[0];
if (pair[1] !== obj[key] || !(key in obj)) return false;
}
return true;
};
};Run a function n times.
_.times = function(n, iteratee, context) {
var accum = Array(Math.max(0, n));
iteratee = createCallback(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) {
if (max == null) {
max = min;
min = 0;
}
return min + Math.floor(Math.random() * (max - min + 1));
};A (possibly faster) way to get the current timestamp as an integer.
_.now = Date.now || function() {
return new Date().getTime();
};List of HTML entities for escaping.
var escapeMap = {
'&': '&',
'<': '<',
'>': '>',
'"': '"',
"'": ''',
'`': '`'
};
var unescapeMap = _.invert(escapeMap);Functions for escaping and unescaping strings to/from HTML interpolation.
var createEscaper = function(map) {
var escaper = function(match) {
return map[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) {
if (object == null) return void 0;
var value = object[property];
return _.isFunction(value) ? object[property]() : value;
};Generate a unique integer id (unique within the entire client session). Useful for temporary DOM ids.
var idCounter = 0;
_.uniqueId = function(prefix) {
var id = ++idCounter + '';
return prefix ? prefix + id : id;
};By default, Underscore uses ERB-style template delimiters, change the following template settings to use alternative delimiters.
_.templateSettings = {
evaluate : /<%([\s\S]+?)%>/g,
interpolate : /<%=([\s\S]+?)%>/g,
escape : /<%-([\s\S]+?)%>/g
};When customizing templateSettings, if you don’t want to define an
interpolation, evaluation or escaping regex, we need one that is
guaranteed not to match.
var noMatch = /(.)^/;Certain characters need to be escaped so that they can be put into a string literal.
var escapes = {
"'": "'",
'\\': '\\',
'\r': 'r',
'\n': 'n',
'\u2028': 'u2028',
'\u2029': 'u2029'
};
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.
NB: oldSettings only exists for backwards compatibility.
_.template = function(text, settings, oldSettings) {
if (!settings && oldSettings) settings = oldSettings;
settings = _.defaults({}, settings, _.templateSettings);Combine delimiters into one regular expression via alternation.
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).replace(escaper, escapeChar);
index = offset + match.length;
if (escape) {
source += "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'";
} else if (interpolate) {
source += "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'";
} else if (evaluate) {
source += "';\n" + evaluate + "\n__p+='";
}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';
try {
var render = new Function(settings.variable || 'obj', '_', source);
} catch (e) {
e.source = source;
throw e;
}
var template = function(data) {
return render.call(this, data, _);
};Provide the compiled source as a convenience for precompilation.
var argument = settings.variable || 'obj';
template.source = 'function(' + argument + '){\n' + source + '}';
return template;
};Add a “chain” function. Start chaining a wrapped Underscore object.
_.chain = function(obj) {
var instance = _(obj);
instance._chain = true;
return instance;
};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) {
return this._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.call(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) {
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];
return result.call(this, obj);
};
});Add all accessor Array functions to the wrapper.
_.each(['concat', 'join', 'slice'], function(name) {
var method = ArrayProto[name];
_.prototype[name] = function() {
return result.call(this, method.apply(this._wrapped, arguments));
};
});Extracts the result from a wrapped and chained object.
_.prototype.value = function() {
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 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));