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// (c) 2011 Jeremy Ashkenas, DocumentCloud Inc.
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// Underscore is freely distributable under the MIT license.
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// Portions of Underscore are inspired or borrowed from Prototype,
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// Oliver Steele's Functional, and John Resig's Micro-Templating.
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// For all details and documentation:
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// http://documentcloud.github.com/underscore
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// Establish the root object, `window` in the browser, or `global` on the server.
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// Save the previous value of the `_` variable.
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var previousUnderscore = root._;
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// Establish the object that gets returned to break out of a loop iteration.
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// Save bytes in the minified (but not gzipped) version:
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var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;
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// Create quick reference variables for speed access to core prototypes.
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var slice = ArrayProto.slice,
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unshift = ArrayProto.unshift,
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toString = ObjProto.toString,
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hasOwnProperty = ObjProto.hasOwnProperty;
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// All **ECMAScript 5** native function implementations that we hope to use
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nativeForEach = ArrayProto.forEach,
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nativeMap = ArrayProto.map,
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nativeReduce = ArrayProto.reduce,
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nativeReduceRight = ArrayProto.reduceRight,
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nativeFilter = ArrayProto.filter,
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nativeEvery = ArrayProto.every,
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nativeSome = ArrayProto.some,
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nativeIndexOf = ArrayProto.indexOf,
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nativeLastIndexOf = ArrayProto.lastIndexOf,
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nativeIsArray = Array.isArray,
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nativeKeys = Object.keys,
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nativeBind = FuncProto.bind;
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// Create a safe reference to the Underscore object for use below.
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var _ = function(obj) { return new wrapper(obj); };
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// Export the Underscore object for **CommonJS**, with backwards-compatibility
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// for the old `require()` API. If we're not in CommonJS, add `_` to the
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if (typeof module !== 'undefined' && module.exports) {
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// Collection Functions
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// --------------------
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// The cornerstone, an `each` implementation, aka `forEach`.
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// Handles objects implementing `forEach`, arrays, and raw objects.
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// Delegates to **ECMAScript 5**'s native `forEach` if available.
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var each = _.each = _.forEach = function(obj, iterator, context) {
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if (obj == null) return;
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if (nativeForEach && obj.forEach === nativeForEach) {
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obj.forEach(iterator, context);
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} else if (_.isNumber(obj.length)) {
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for (var i = 0, l = obj.length; i < l; i++) {
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if (iterator.call(context, obj[i], i, obj) === breaker) return;
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for (var key in obj) {
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if (hasOwnProperty.call(obj, key)) {
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if (iterator.call(context, obj[key], key, obj) === breaker) return;
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// Return the results of applying the iterator to each element.
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// Delegates to **ECMAScript 5**'s native `map` if available.
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_.map = function(obj, iterator, context) {
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if (obj == null) return results;
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if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
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each(obj, function(value, index, list) {
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results[results.length] = iterator.call(context, value, index, list);
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// **Reduce** builds up a single result from a list of values, aka `inject`,
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// or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
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_.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
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var initial = memo !== void 0;
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if (obj == null) obj = [];
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if (nativeReduce && obj.reduce === nativeReduce) {
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if (context) iterator = _.bind(iterator, context);
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return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
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each(obj, function(value, index, list) {
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if (!initial && index === 0) {
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memo = iterator.call(context, memo, value, index, list);
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if (!initial) throw new TypeError("Reduce of empty array with no initial value");
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// The right-associative version of reduce, also known as `foldr`.
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// Delegates to **ECMAScript 5**'s native `reduceRight` if available.
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_.reduceRight = _.foldr = function(obj, iterator, memo, context) {
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if (obj == null) obj = [];
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if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
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if (context) iterator = _.bind(iterator, context);
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return memo !== void 0 ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
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var reversed = (_.isArray(obj) ? obj.slice() : _.toArray(obj)).reverse();
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return _.reduce(reversed, iterator, memo, context);
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// Return the first value which passes a truth test. Aliased as `detect`.
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_.find = _.detect = function(obj, iterator, context) {
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any(obj, function(value, index, list) {
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if (iterator.call(context, value, index, list)) {
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// Return all the elements that pass a truth test.
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// Delegates to **ECMAScript 5**'s native `filter` if available.
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// Aliased as `select`.
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_.filter = _.select = function(obj, iterator, context) {
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if (obj == null) return results;
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if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
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each(obj, function(value, index, list) {
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if (iterator.call(context, value, index, list)) results[results.length] = value;
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// Return all the elements for which a truth test fails.
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_.reject = function(obj, iterator, context) {
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if (obj == null) return results;
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each(obj, function(value, index, list) {
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if (!iterator.call(context, value, index, list)) results[results.length] = value;
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// Determine whether all of the elements match a truth test.
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// Delegates to **ECMAScript 5**'s native `every` if available.
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_.every = _.all = function(obj, iterator, context) {
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if (obj == null) return result;
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if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
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each(obj, function(value, index, list) {
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if (!(result = result && iterator.call(context, value, index, list))) return breaker;
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// Determine if at least one element in the object matches a truth test.
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// Delegates to **ECMAScript 5**'s native `some` if available.
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var any = _.some = _.any = function(obj, iterator, context) {
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iterator || (iterator = _.identity);
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if (obj == null) return result;
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if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
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each(obj, function(value, index, list) {
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if (result = iterator.call(context, value, index, list)) return breaker;
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// Determine if a given value is included in the array or object using `===`.
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// Aliased as `contains`.
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_.include = _.contains = function(obj, target) {
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if (obj == null) return found;
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if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
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any(obj, function(value) {
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if (found = value === target) return true;
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// Invoke a method (with arguments) on every item in a collection.
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_.invoke = function(obj, method) {
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var args = slice.call(arguments, 2);
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return _.map(obj, function(value) {
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return (method.call ? method || value : value[method]).apply(value, args);
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// Convenience version of a common use case of `map`: fetching a property.
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_.pluck = function(obj, key) {
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return _.map(obj, function(value){ return value[key]; });
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// Return the maximum element or (element-based computation).
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_.max = function(obj, iterator, context) {
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if (!iterator && _.isArray(obj)) return Math.max.apply(Math, obj);
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var result = {computed : -Infinity};
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each(obj, function(value, index, list) {
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var computed = iterator ? iterator.call(context, value, index, list) : value;
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computed >= result.computed && (result = {value : value, computed : computed});
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// Return the minimum element (or element-based computation).
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_.min = function(obj, iterator, context) {
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if (!iterator && _.isArray(obj)) return Math.min.apply(Math, obj);
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var result = {computed : Infinity};
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each(obj, function(value, index, list) {
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var computed = iterator ? iterator.call(context, value, index, list) : value;
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computed < result.computed && (result = {value : value, computed : computed});
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// Sort the object's values by a criterion produced by an iterator.
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_.sortBy = function(obj, iterator, context) {
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return _.pluck(_.map(obj, function(value, index, list) {
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criteria : iterator.call(context, value, index, list)
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}).sort(function(left, right) {
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var a = left.criteria, b = right.criteria;
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return a < b ? -1 : a > b ? 1 : 0;
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// Use a comparator function to figure out at what index an object should
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// be inserted so as to maintain order. Uses binary search.
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_.sortedIndex = function(array, obj, iterator) {
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iterator || (iterator = _.identity);
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var low = 0, high = array.length;
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var mid = (low + high) >> 1;
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iterator(array[mid]) < iterator(obj) ? low = mid + 1 : high = mid;
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// Safely convert anything iterable into a real, live array.
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_.toArray = function(iterable) {
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if (!iterable) return [];
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if (iterable.toArray) return iterable.toArray();
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if (_.isArray(iterable)) return iterable;
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if (_.isArguments(iterable)) return slice.call(iterable);
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return _.values(iterable);
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// Return the number of elements in an object.
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_.size = function(obj) {
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return _.toArray(obj).length;
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// Get the first element of an array. Passing **n** will return the first N
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// values in the array. Aliased as `head`. The **guard** check allows it to work
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_.first = _.head = function(array, n, guard) {
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return (n != null) && !guard ? slice.call(array, 0, n) : array[0];
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// Returns everything but the first entry of the array. Aliased as `tail`.
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// Especially useful on the arguments object. Passing an **index** will return
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// the rest of the values in the array from that index onward. The **guard**
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// check allows it to work with `_.map`.
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_.rest = _.tail = function(array, index, guard) {
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return slice.call(array, (index == null) || guard ? 1 : index);
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// Get the last element of an array.
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_.last = function(array) {
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return array[array.length - 1];
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// Trim out all falsy values from an array.
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_.compact = function(array) {
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return _.filter(array, function(value){ return !!value; });
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// Return a completely flattened version of an array.
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_.flatten = function(array) {
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return _.reduce(array, function(memo, value) {
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if (_.isArray(value)) return memo.concat(_.flatten(value));
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memo[memo.length] = value;
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// Return a version of the array that does not contain the specified value(s).
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_.without = function(array) {
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var values = slice.call(arguments, 1);
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return _.filter(array, function(value){ return !_.include(values, value); });
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// Produce a duplicate-free version of the array. If the array has already
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// been sorted, you have the option of using a faster algorithm.
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// Aliased as `unique`.
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_.uniq = _.unique = function(array, isSorted) {
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return _.reduce(array, function(memo, el, i) {
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if (0 == i || (isSorted === true ? _.last(memo) != el : !_.include(memo, el))) memo[memo.length] = el;
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// Produce an array that contains every item shared between all the
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_.intersect = function(array) {
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var rest = slice.call(arguments, 1);
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return _.filter(_.uniq(array), function(item) {
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return _.every(rest, function(other) {
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return _.indexOf(other, item) >= 0;
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// Zip together multiple lists into a single array -- elements that share
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// an index go together.
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var args = slice.call(arguments);
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var length = _.max(_.pluck(args, 'length'));
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var results = new Array(length);
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for (var i = 0; i < length; i++) results[i] = _.pluck(args, "" + i);
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// If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
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// we need this function. Return the position of the first occurrence of an
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// item in an array, or -1 if the item is not included in the array.
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// Delegates to **ECMAScript 5**'s native `indexOf` if available.
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// If the array is large and already in sort order, pass `true`
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// for **isSorted** to use binary search.
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_.indexOf = function(array, item, isSorted) {
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if (array == null) return -1;
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i = _.sortedIndex(array, item);
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return array[i] === item ? i : -1;
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if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);
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for (i = 0, l = array.length; i < l; i++) if (array[i] === item) return i;
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// Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
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_.lastIndexOf = function(array, item) {
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if (array == null) return -1;
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if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);
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var i = array.length;
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while (i--) if (array[i] === item) return i;
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// Generate an integer Array containing an arithmetic progression. A port of
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// the native Python `range()` function. See
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// [the Python documentation](http://docs.python.org/library/functions.html#range).
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_.range = function(start, stop, step) {
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if (arguments.length <= 1) {
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step = arguments[2] || 1;
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var len = Math.max(Math.ceil((stop - start) / step), 0);
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var range = new Array(len);
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range[idx++] = start;
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// Function (ahem) Functions
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// ------------------
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// Create a function bound to a given object (assigning `this`, and arguments,
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// optionally). Binding with arguments is also known as `curry`.
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// Delegates to **ECMAScript 5**'s native `Function.bind` if available.
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// We check for `func.bind` first, to fail fast when `func` is undefined.
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_.bind = function(func, obj) {
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if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
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var args = slice.call(arguments, 2);
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return func.apply(obj, args.concat(slice.call(arguments)));
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// Bind all of an object's methods to that object. Useful for ensuring that
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// all callbacks defined on an object belong to it.
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_.bindAll = function(obj) {
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var funcs = slice.call(arguments, 1);
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if (funcs.length == 0) funcs = _.functions(obj);
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each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
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// Memoize an expensive function by storing its results.
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_.memoize = function(func, hasher) {
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hasher || (hasher = _.identity);
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var key = hasher.apply(this, arguments);
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return hasOwnProperty.call(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
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// Delays a function for the given number of milliseconds, and then calls
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// it with the arguments supplied.
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_.delay = function(func, wait) {
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var args = slice.call(arguments, 2);
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return setTimeout(function(){ return func.apply(func, args); }, wait);
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// Defers a function, scheduling it to run after the current call stack has
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_.defer = function(func) {
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return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));
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// Internal function used to implement `_.throttle` and `_.debounce`.
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var limit = function(func, wait, debounce) {
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var context = this, args = arguments;
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var throttler = function() {
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func.apply(context, args);
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if (debounce) clearTimeout(timeout);
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if (debounce || !timeout) timeout = setTimeout(throttler, wait);
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// Returns a function, that, when invoked, will only be triggered at most once
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// during a given window of time.
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_.throttle = function(func, wait) {
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return limit(func, wait, false);
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// Returns a function, that, as long as it continues to be invoked, will not
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// be triggered. The function will be called after it stops being called for
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_.debounce = function(func, wait) {
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return limit(func, wait, true);
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// Returns a function that will be executed at most one time, no matter how
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// often you call it. Useful for lazy initialization.
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_.once = function(func) {
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var ran = false, memo;
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if (ran) return memo;
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return memo = func.apply(this, arguments);
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// Returns the first function passed as an argument to the second,
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// allowing you to adjust arguments, run code before and after, and
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// conditionally execute the original function.
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_.wrap = function(func, wrapper) {
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var args = [func].concat(slice.call(arguments));
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return wrapper.apply(this, args);
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// Returns a function that is the composition of a list of functions, each
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// consuming the return value of the function that follows.
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_.compose = function() {
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var funcs = slice.call(arguments);
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var args = slice.call(arguments);
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for (var i=funcs.length-1; i >= 0; i--) {
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args = [funcs[i].apply(this, args)];
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// Returns a function that will only be executed after being called N times.
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_.after = function(times, func) {
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if (--times < 1) { return func.apply(this, arguments); }
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// Retrieve the names of an object's properties.
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// Delegates to **ECMAScript 5**'s native `Object.keys`
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_.keys = nativeKeys || function(obj) {
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if (obj !== Object(obj)) throw new TypeError('Invalid object');
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for (var key in obj) if (hasOwnProperty.call(obj, key)) keys[keys.length] = key;
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// Retrieve the values of an object's properties.
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_.values = function(obj) {
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return _.map(obj, _.identity);
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// Return a sorted list of the function names available on the object.
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// Aliased as `methods`
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_.functions = _.methods = function(obj) {
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return _.filter(_.keys(obj), function(key){ return _.isFunction(obj[key]); }).sort();
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// Extend a given object with all the properties in passed-in object(s).
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_.extend = function(obj) {
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each(slice.call(arguments, 1), function(source) {
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for (var prop in source) {
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if (source[prop] !== void 0) obj[prop] = source[prop];
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// Fill in a given object with default properties.
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_.defaults = function(obj) {
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each(slice.call(arguments, 1), function(source) {
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for (var prop in source) {
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if (obj[prop] == null) obj[prop] = source[prop];
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// Create a (shallow-cloned) duplicate of an object.
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_.clone = function(obj) {
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return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
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// Invokes interceptor with the obj, and then returns obj.
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// The primary purpose of this method is to "tap into" a method chain, in
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// order to perform operations on intermediate results within the chain.
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_.tap = function(obj, interceptor) {
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// Perform a deep comparison to check if two objects are equal.
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_.isEqual = function(a, b) {
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// Check object identity.
579
if (a === b) return true;
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var atype = typeof(a), btype = typeof(b);
582
if (atype != btype) return false;
583
// Basic equality test (watch out for coercions).
584
if (a == b) return true;
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// One is falsy and the other truthy.
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if ((!a && b) || (a && !b)) return false;
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// Unwrap any wrapped objects.
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if (a._chain) a = a._wrapped;
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if (b._chain) b = b._wrapped;
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// One of them implements an isEqual()?
591
if (a.isEqual) return a.isEqual(b);
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// Check dates' integer values.
593
if (_.isDate(a) && _.isDate(b)) return a.getTime() === b.getTime();
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if (_.isNaN(a) && _.isNaN(b)) return false;
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// Compare regular expressions.
597
if (_.isRegExp(a) && _.isRegExp(b))
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return a.source === b.source &&
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a.global === b.global &&
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a.ignoreCase === b.ignoreCase &&
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a.multiline === b.multiline;
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// If a is not an object by this point, we can't handle it.
603
if (atype !== 'object') return false;
604
// Check for different array lengths before comparing contents.
605
if (a.length && (a.length !== b.length)) return false;
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// Nothing else worked, deep compare the contents.
607
var aKeys = _.keys(a), bKeys = _.keys(b);
608
// Different object sizes?
609
if (aKeys.length != bKeys.length) return false;
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// Recursive comparison of contents.
611
for (var key in a) if (!(key in b) || !_.isEqual(a[key], b[key])) return false;
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// Is a given array or object empty?
616
_.isEmpty = function(obj) {
617
if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
618
for (var key in obj) if (hasOwnProperty.call(obj, key)) return false;
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// Is a given value a DOM element?
623
_.isElement = function(obj) {
624
return !!(obj && obj.nodeType == 1);
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// Is a given value an array?
628
// Delegates to ECMA5's native Array.isArray
629
_.isArray = nativeIsArray || function(obj) {
630
return toString.call(obj) === '[object Array]';
633
// Is a given variable an arguments object?
634
_.isArguments = function(obj) {
635
return !!(obj && hasOwnProperty.call(obj, 'callee'));
638
// Is a given value a function?
639
_.isFunction = function(obj) {
640
return !!(obj && obj.constructor && obj.call && obj.apply);
643
// Is a given value a string?
644
_.isString = function(obj) {
645
return !!(obj === '' || (obj && obj.charCodeAt && obj.substr));
648
// Is a given value a number?
649
_.isNumber = function(obj) {
650
return !!(obj === 0 || (obj && obj.toExponential && obj.toFixed));
653
// Is the given value `NaN`? `NaN` happens to be the only value in JavaScript
654
// that does not equal itself.
655
_.isNaN = function(obj) {
659
// Is a given value a boolean?
660
_.isBoolean = function(obj) {
661
return obj === true || obj === false;
664
// Is a given value a date?
665
_.isDate = function(obj) {
666
return !!(obj && obj.getTimezoneOffset && obj.setUTCFullYear);
669
// Is the given value a regular expression?
670
_.isRegExp = function(obj) {
671
return !!(obj && obj.test && obj.exec && (obj.ignoreCase || obj.ignoreCase === false));
674
// Is a given value equal to null?
675
_.isNull = function(obj) {
679
// Is a given variable undefined?
680
_.isUndefined = function(obj) {
681
return obj === void 0;
687
// Run Underscore.js in *noConflict* mode, returning the `_` variable to its
688
// previous owner. Returns a reference to the Underscore object.
689
_.noConflict = function() {
690
root._ = previousUnderscore;
694
// Keep the identity function around for default iterators.
695
_.identity = function(value) {
699
// Run a function **n** times.
700
_.times = function (n, iterator, context) {
701
for (var i = 0; i < n; i++) iterator.call(context, i);
704
// Add your own custom functions to the Underscore object, ensuring that
705
// they're correctly added to the OOP wrapper as well.
706
_.mixin = function(obj) {
707
each(_.functions(obj), function(name){
708
addToWrapper(name, _[name] = obj[name]);
712
// Generate a unique integer id (unique within the entire client session).
713
// Useful for temporary DOM ids.
715
_.uniqueId = function(prefix) {
716
var id = idCounter++;
717
return prefix ? prefix + id : id;
720
// By default, Underscore uses ERB-style template delimiters, change the
721
// following template settings to use alternative delimiters.
722
_.templateSettings = {
723
evaluate : /<%([\s\S]+?)%>/g,
724
interpolate : /<%=([\s\S]+?)%>/g
727
// JavaScript micro-templating, similar to John Resig's implementation.
728
// Underscore templating handles arbitrary delimiters, preserves whitespace,
729
// and correctly escapes quotes within interpolated code.
730
_.template = function(str, data) {
731
var c = _.templateSettings;
732
var tmpl = 'var __p=[],print=function(){__p.push.apply(__p,arguments);};' +
733
'with(obj||{}){__p.push(\'' +
734
str.replace(/\\/g, '\\\\')
735
.replace(/'/g, "\\'")
736
.replace(c.interpolate, function(match, code) {
737
return "'," + code.replace(/\\'/g, "'") + ",'";
739
.replace(c.evaluate || null, function(match, code) {
740
return "');" + code.replace(/\\'/g, "'")
741
.replace(/[\r\n\t]/g, ' ') + "__p.push('";
743
.replace(/\r/g, '\\r')
744
.replace(/\n/g, '\\n')
745
.replace(/\t/g, '\\t')
746
+ "');}return __p.join('');";
747
var func = new Function('obj', tmpl);
748
return data ? func(data) : func;
754
// If Underscore is called as a function, it returns a wrapped object that
755
// can be used OO-style. This wrapper holds altered versions of all the
756
// underscore functions. Wrapped objects may be chained.
757
var wrapper = function(obj) { this._wrapped = obj; };
759
// Expose `wrapper.prototype` as `_.prototype`
760
_.prototype = wrapper.prototype;
762
// Helper function to continue chaining intermediate results.
763
var result = function(obj, chain) {
764
return chain ? _(obj).chain() : obj;
767
// A method to easily add functions to the OOP wrapper.
768
var addToWrapper = function(name, func) {
769
wrapper.prototype[name] = function() {
770
var args = slice.call(arguments);
771
unshift.call(args, this._wrapped);
772
return result(func.apply(_, args), this._chain);
776
// Add all of the Underscore functions to the wrapper object.
779
// Add all mutator Array functions to the wrapper.
780
each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
781
var method = ArrayProto[name];
782
wrapper.prototype[name] = function() {
783
method.apply(this._wrapped, arguments);
784
return result(this._wrapped, this._chain);
788
// Add all accessor Array functions to the wrapper.
789
each(['concat', 'join', 'slice'], function(name) {
790
var method = ArrayProto[name];
791
wrapper.prototype[name] = function() {
792
return result(method.apply(this._wrapped, arguments), this._chain);
796
// Start chaining a wrapped Underscore object.
797
wrapper.prototype.chain = function() {
802
// Extracts the result from a wrapped and chained object.
803
wrapper.prototype.value = function() {
804
return this._wrapped;
added
removed
doc/sphinx/=build/html/_static/underscore.js
