underscore.js | |
|---|---|
| (function() { |
Baseline setup | |
| Establish the root object, | var root = this; |
| Save the previous value of the | var previousUnderscore = root._; |
| Establish the object that gets thrown to break out of a loop iteration. | var breaker = typeof StopIteration !== 'undefined' ? StopIteration : '__break__'; |
| Quick regexp-escaping function, because JS doesn't have a | var escapeRegExp = function(s) { return s.replace(/([.*+?^${}()|[\]\/\\])/g, '\\$1'); }; |
| Save bytes in the minified (but not gzipped) version: | var ArrayProto = Array.prototype, ObjProto = Object.prototype; |
| Create quick reference variables for speed access to core prototypes. | var slice = ArrayProto.slice,
+ unshift = ArrayProto.unshift,
+ toString = ObjProto.toString,
+ hasOwnProperty = ObjProto.hasOwnProperty,
+ propertyIsEnumerable = ObjProto.propertyIsEnumerable; |
| All ECMA5 native implementations we hope to use are declared here. | var
+ nativeForEach = ArrayProto.forEach,
+ nativeMap = ArrayProto.map,
+ nativeReduce = ArrayProto.reduce,
+ nativeReduceRight = ArrayProto.reduceRight,
+ nativeFilter = ArrayProto.filter,
+ nativeEvery = ArrayProto.every,
+ nativeSome = ArrayProto.some,
+ nativeIndexOf = ArrayProto.indexOf,
+ nativeLastIndexOf = ArrayProto.lastIndexOf,
+ nativeIsArray = Array.isArray,
+ nativeKeys = Object.keys; |
| Create a safe reference to the Underscore object for use below. | var _ = function(obj) { return new wrapper(obj); }; |
| Export the Underscore object for CommonJS. | if (typeof exports !== 'undefined') exports._ = _; |
| Export Underscore to global scope. | root._ = _; |
| Current version. | _.VERSION = '1.1.0'; |
Collection Functions | |
| The cornerstone, an each implementation.
+Handles objects implementing | var each = _.forEach = function(obj, iterator, context) {
+ try {
+ if (nativeForEach && obj.forEach === nativeForEach) {
+ obj.forEach(iterator, context);
+ } else if (_.isNumber(obj.length)) {
+ for (var i = 0, l = obj.length; i < l; i++) iterator.call(context, obj[i], i, obj);
+ } else {
+ for (var key in obj) {
+ if (hasOwnProperty.call(obj, key)) iterator.call(context, obj[key], key, obj);
+ }
+ }
+ } catch(e) {
+ if (e != breaker) throw e;
+ }
+ return obj;
+ }; |
| Return the results of applying the iterator to each element.
+Delegates to JavaScript 1.6's native | _.map = function(obj, iterator, context) {
+ if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
+ var results = [];
+ each(obj, function(value, index, list) {
+ results[results.length] = iterator.call(context, value, index, list);
+ });
+ return results;
+ }; |
| Reduce builds up a single result from a list of values, aka | _.reduce = function(obj, iterator, memo, context) {
+ if (nativeReduce && obj.reduce === nativeReduce) {
+ if (context) iterator = _.bind(iterator, context);
+ return obj.reduce(iterator, memo);
+ }
+ each(obj, function(value, index, list) {
+ memo = iterator.call(context, memo, value, index, list);
+ });
+ return memo;
+ }; |
| The right-associative version of reduce, also known as | _.reduceRight = function(obj, iterator, memo, context) {
+ if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
+ if (context) iterator = _.bind(iterator, context);
+ return obj.reduceRight(iterator, memo);
+ }
+ var reversed = _.clone(_.toArray(obj)).reverse();
+ return _.reduce(reversed, iterator, memo, context);
+ }; |
| Return the first value which passes a truth test. | _.detect = function(obj, iterator, context) {
+ var result;
+ each(obj, function(value, index, list) {
+ if (iterator.call(context, value, index, list)) {
+ result = value;
+ _.breakLoop();
+ }
+ });
+ return result;
+ }; |
| Return all the elements that pass a truth test. +Delegates to JavaScript 1.6's native filter if available. | _.filter = function(obj, iterator, context) {
+ if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
+ var results = [];
+ each(obj, function(value, index, list) {
+ if (iterator.call(context, value, index, list)) results[results.length] = value;
+ });
+ return results;
+ }; |
| Return all the elements for which a truth test fails. | _.reject = function(obj, iterator, context) {
+ var results = [];
+ each(obj, function(value, index, list) {
+ if (!iterator.call(context, value, index, list)) results[results.length] = value;
+ });
+ return results;
+ }; |
| Determine whether all of the elements match a truth test. +Delegates to JavaScript 1.6's native every if available. | _.every = function(obj, iterator, context) {
+ iterator = iterator || _.identity;
+ if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
+ var result = true;
+ each(obj, function(value, index, list) {
+ if (!(result = result && iterator.call(context, value, index, list))) _.breakLoop();
+ });
+ return result;
+ }; |
| Determine if at least one element in the object matches a truth test. +Delegates to JavaScript 1.6's native some if available. | _.some = function(obj, iterator, context) {
+ iterator = iterator || _.identity;
+ if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
+ var result = false;
+ each(obj, function(value, index, list) {
+ if (result = iterator.call(context, value, index, list)) _.breakLoop();
+ });
+ return result;
+ }; |
| Determine if a given value is included in the array or object using '==='. | _.include = function(obj, target) {
+ if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
+ var found = false;
+ each(obj, function(value) {
+ if (found = value === target) _.breakLoop();
+ });
+ return found;
+ }; |
| Invoke a method with arguments on every item in a collection. | _.invoke = function(obj, method) {
+ var args = _.rest(arguments, 2);
+ return _.map(obj, function(value) {
+ return (method ? value[method] : value).apply(value, args);
+ });
+ }; |
| Convenience version of a common use case of map: fetching a property. | _.pluck = function(obj, key) {
+ return _.map(obj, function(value){ return value[key]; });
+ }; |
| Return the maximum item or (item-based computation). | _.max = function(obj, iterator, context) {
+ if (!iterator && _.isArray(obj)) return Math.max.apply(Math, obj);
+ var result = {computed : -Infinity};
+ each(obj, function(value, index, list) {
+ var computed = iterator ? iterator.call(context, value, index, list) : value;
+ computed >= result.computed && (result = {value : value, computed : computed});
+ });
+ return result.value;
+ }; |
| Return the minimum element (or element-based computation). | _.min = function(obj, iterator, context) {
+ if (!iterator && _.isArray(obj)) return Math.min.apply(Math, obj);
+ var result = {computed : Infinity};
+ each(obj, function(value, index, list) {
+ var computed = iterator ? iterator.call(context, value, index, list) : value;
+ computed < result.computed && (result = {value : value, computed : computed});
+ });
+ return result.value;
+ }; |
| Sort the object's values by a criterion produced by an iterator. | _.sortBy = function(obj, iterator, context) {
+ return _.pluck(_.map(obj, function(value, index, list) {
+ return {
+ value : value,
+ criteria : iterator.call(context, value, index, list)
+ };
+ }).sort(function(left, right) {
+ var a = left.criteria, b = right.criteria;
+ return a < b ? -1 : a > b ? 1 : 0;
+ }), 'value');
+ }; |
| Use a comparator function to figure out at what index an object should +be inserted so as to maintain order. Uses binary search. | _.sortedIndex = function(array, obj, iterator) {
+ iterator = iterator || _.identity;
+ var low = 0, high = array.length;
+ while (low < high) {
+ var mid = (low + high) >> 1;
+ iterator(array[mid]) < iterator(obj) ? low = mid + 1 : high = mid;
+ }
+ return low;
+ }; |
| Convert anything iterable into a real, live array. | _.toArray = function(iterable) {
+ if (!iterable) return [];
+ if (iterable.toArray) return iterable.toArray();
+ if (_.isArray(iterable)) return iterable;
+ if (_.isArguments(iterable)) return slice.call(iterable);
+ return _.values(iterable);
+ }; |
| Return the number of elements in an object. | _.size = function(obj) {
+ return _.toArray(obj).length;
+ }; |
Array Functions | |
| Get the first element of an array. Passing "n" will return the first N +values in the array. Aliased as "head". The "guard" check allows it to work +with _.map. | _.first = function(array, n, guard) {
+ return n && !guard ? slice.call(array, 0, n) : array[0];
+ }; |
| Returns everything but the first entry of the array. Aliased as "tail". +Especially useful on the arguments object. Passing an "index" will return +the rest of the values in the array from that index onward. The "guard" +check allows it to work with _.map. | _.rest = function(array, index, guard) {
+ return slice.call(array, _.isUndefined(index) || guard ? 1 : index);
+ }; |
| Get the last element of an array. | _.last = function(array) {
+ return array[array.length - 1];
+ }; |
| Trim out all falsy values from an array. | _.compact = function(array) {
+ return _.filter(array, function(value){ return !!value; });
+ }; |
| Return a completely flattened version of an array. | _.flatten = function(array) {
+ return _.reduce(array, function(memo, value) {
+ if (_.isArray(value)) return memo.concat(_.flatten(value));
+ memo[memo.length] = value;
+ return memo;
+ }, []);
+ }; |
| Return a version of the array that does not contain the specified value(s). | _.without = function(array) {
+ var values = _.rest(arguments);
+ return _.filter(array, function(value){ return !_.include(values, value); });
+ }; |
| Produce a duplicate-free version of the array. If the array has already +been sorted, you have the option of using a faster algorithm. | _.uniq = function(array, isSorted) {
+ return _.reduce(array, function(memo, el, i) {
+ if (0 == i || (isSorted === true ? _.last(memo) != el : !_.include(memo, el))) memo[memo.length] = el;
+ return memo;
+ }, []);
+ }; |
| Produce an array that contains every item shared between all the +passed-in arrays. | _.intersect = function(array) {
+ var rest = _.rest(arguments);
+ return _.filter(_.uniq(array), function(item) {
+ return _.every(rest, function(other) {
+ return _.indexOf(other, item) >= 0;
+ });
+ });
+ }; |
| Zip together multiple lists into a single array -- elements that share +an index go together. | _.zip = function() {
+ var args = _.toArray(arguments);
+ var length = _.max(_.pluck(args, 'length'));
+ var results = new Array(length);
+ for (var i = 0; i < length; i++) results[i] = _.pluck(args, "" + i);
+ return results;
+ }; |
| If the browser doesn't supply us with indexOf (I'm looking at you, MSIE), +we need this function. Return the position of the first occurence of an +item in an array, or -1 if the item is not included in the array. +Delegates to JavaScript 1.8's native indexOf if available. | _.indexOf = function(array, item) {
+ if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);
+ for (var i = 0, l = array.length; i < l; i++) if (array[i] === item) return i;
+ return -1;
+ }; |
| Delegates to JavaScript 1.6's native lastIndexOf if available. | _.lastIndexOf = function(array, item) {
+ if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);
+ var i = array.length;
+ while (i--) if (array[i] === item) return i;
+ return -1;
+ }; |
| Generate an integer Array containing an arithmetic progression. A port of +the native Python range() function. See: +http://docs.python.org/library/functions.html#range | _.range = function(start, stop, step) {
+ var a = _.toArray(arguments);
+ var solo = a.length <= 1;
+ var start = solo ? 0 : a[0], stop = solo ? a[0] : a[1], step = a[2] || 1;
+ var len = Math.ceil((stop - start) / step);
+ if (len <= 0) return [];
+ var range = new Array(len);
+ for (var i = start, idx = 0; true; i += step) {
+ if ((step > 0 ? i - stop : stop - i) >= 0) return range;
+ range[idx++] = i;
+ }
+ }; |
Function Functions | |
| Create a function bound to a given object (assigning 'this', and arguments, +optionally). Binding with arguments is also known as 'curry'. | _.bind = function(func, obj) {
+ var args = _.rest(arguments, 2);
+ return function() {
+ return func.apply(obj || {}, args.concat(_.toArray(arguments)));
+ };
+ }; |
| Bind all of an object's methods to that object. Useful for ensuring that +all callbacks defined on an object belong to it. | _.bindAll = function(obj) {
+ var funcs = _.rest(arguments);
+ if (funcs.length == 0) funcs = _.functions(obj);
+ each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });
+ return obj;
+ }; |
| Memoize an expensive function by storing its results. | _.memoize = function(func, hasher) {
+ var memo = {};
+ hasher = hasher || _.identity;
+ return function() {
+ var key = hasher.apply(this, arguments);
+ return key in memo ? memo[key] : (memo[key] = func.apply(this, arguments));
+ };
+ }; |
| Delays a function for the given number of milliseconds, and then calls +it with the arguments supplied. | _.delay = function(func, wait) {
+ var args = _.rest(arguments, 2);
+ return setTimeout(function(){ return func.apply(func, 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(_.rest(arguments)));
+ }; |
| 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 function() {
+ var args = [func].concat(_.toArray(arguments));
+ return wrapper.apply(wrapper, args);
+ };
+ }; |
| Returns a function that is the composition of a list of functions, each +consuming the return value of the function that follows. | _.compose = function() {
+ var funcs = _.toArray(arguments);
+ return function() {
+ var args = _.toArray(arguments);
+ for (var i=funcs.length-1; i >= 0; i--) {
+ args = [funcs[i].apply(this, args)];
+ }
+ return args[0];
+ };
+ }; |
Object Functions | |
| Retrieve the names of an object's properties. +Delegates to ECMA5's native Object.keys | _.keys = nativeKeys || function(obj) {
+ if (_.isArray(obj)) return _.range(0, obj.length);
+ var keys = [];
+ for (var key in obj) if (hasOwnProperty.call(obj, key)) keys[keys.length] = key;
+ return keys;
+ }; |
| Retrieve the values of an object's properties. | _.values = function(obj) {
+ return _.map(obj, _.identity);
+ }; |
| Return a sorted list of the function names available on the object. | _.functions = function(obj) {
+ return _.filter(_.keys(obj), function(key){ return _.isFunction(obj[key]); }).sort();
+ }; |
| Extend a given object with all the properties in passed-in object(s). | _.extend = function(obj) {
+ each(_.rest(arguments), function(source) {
+ for (var prop in source) obj[prop] = source[prop];
+ });
+ return obj;
+ }; |
| Create a (shallow-cloned) duplicate of an object. | _.clone = function(obj) {
+ if (_.isArray(obj)) return obj.slice(0);
+ return _.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;
+ }; |
| Perform a deep comparison to check if two objects are equal. | _.isEqual = function(a, b) { |
| Check object identity. | if (a === b) return true; |
| Different types? | var atype = typeof(a), btype = typeof(b);
+ if (atype != btype) return false; |
| Basic equality test (watch out for coercions). | if (a == b) return true; |
| One is falsy and the other truthy. | if ((!a && b) || (a && !b)) return false; |
| One of them implements an isEqual()? | if (a.isEqual) return a.isEqual(b); |
| Check dates' integer values. | if (_.isDate(a) && _.isDate(b)) return a.getTime() === b.getTime(); |
| Both are NaN? | if (_.isNaN(a) && _.isNaN(b)) return false; |
| Compare regular expressions. | if (_.isRegExp(a) && _.isRegExp(b))
+ return a.source === b.source &&
+ a.global === b.global &&
+ a.ignoreCase === b.ignoreCase &&
+ a.multiline === b.multiline; |
| If a is not an object by this point, we can't handle it. | if (atype !== 'object') return false; |
| Check for different array lengths before comparing contents. | if (a.length && (a.length !== b.length)) return false; |
| Nothing else worked, deep compare the contents. | var aKeys = _.keys(a), bKeys = _.keys(b); |
| Different object sizes? | if (aKeys.length != bKeys.length) return false; |
| Recursive comparison of contents. | for (var key in a) if (!(key in b) || !_.isEqual(a[key], b[key])) return false;
+ return true;
+ }; |
| Is a given array or object empty? | _.isEmpty = function(obj) {
+ if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
+ for (var key in obj) if (hasOwnProperty.call(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 !!(obj && obj.concat && obj.unshift && !obj.callee);
+ }; |
| Is a given variable an arguments object? | _.isArguments = function(obj) {
+ return !!(obj && obj.callee);
+ }; |
| Is a given value a function? | _.isFunction = function(obj) {
+ return !!(obj && obj.constructor && obj.call && obj.apply);
+ }; |
| Is a given value a string? | _.isString = function(obj) {
+ return !!(obj === '' || (obj && obj.charCodeAt && obj.substr));
+ }; |
| Is a given value a number? | _.isNumber = function(obj) {
+ return (obj === +obj) || (toString.call(obj) === '[object Number]');
+ }; |
| Is a given value a boolean? | _.isBoolean = function(obj) {
+ return obj === true || obj === false;
+ }; |
| Is a given value a date? | _.isDate = function(obj) {
+ return !!(obj && obj.getTimezoneOffset && obj.setUTCFullYear);
+ }; |
| Is the given value a regular expression? | _.isRegExp = function(obj) {
+ return !!(obj && obj.test && obj.exec && (obj.ignoreCase || obj.ignoreCase === false));
+ }; |
| Is the given value NaN -- this one is interesting. NaN != NaN, and +isNaN(undefined) == true, so we make sure it's a number first. | _.isNaN = function(obj) {
+ return _.isNumber(obj) && isNaN(obj);
+ }; |
| Is a given value equal to null? | _.isNull = function(obj) {
+ return obj === null;
+ }; |
| Is a given variable undefined? | _.isUndefined = function(obj) {
+ return typeof obj == 'undefined';
+ }; |
Utility Functions | |
| 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 iterators. | _.identity = function(value) {
+ return value;
+ }; |
| Run a function n times. | _.times = function (n, iterator, context) {
+ for (var i = 0; i < n; i++) iterator.call(context, i);
+ }; |
| Break out of the middle of an iteration. | _.breakLoop = function() {
+ throw breaker;
+ }; |
| Add your own custom functions to the Underscore object, ensuring that +they're correctly added to the OOP wrapper as well. | _.mixin = function(obj) {
+ each(_.functions(obj), function(name){
+ addToWrapper(name, _[name] = obj[name]);
+ });
+ }; |
| 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 : /<%(.+?)%>/g,
+ interpolate : /<%=(.+?)%>/g
+ }; |
| JavaScript templating a-la ERB, pilfered from John Resig's +"Secrets of the JavaScript Ninja", page 83. +Single-quote fix from Rick Strahl's version. +With alterations for arbitrary delimiters, and to preserve whitespace. | _.template = function(str, data) {
+ var c = _.templateSettings;
+ var tmpl = 'var __p=[],print=function(){__p.push.apply(__p,arguments);};' +
+ 'with(obj||{}){__p.push(\'' +
+ str.replace(/'/g, "\\'")
+ .replace(c.interpolate, function(match, code) {
+ return "'," + code.replace(/\\'/g, "'") + ",'";
+ })
+ .replace(c.evaluate || null, function(match, code) {
+ return "');" + code.replace(/\\'/g, "'")
+ .replace(/[\r\n\t]/g, ' ') + "__p.push('";
+ })
+ .replace(/\r/g, '\\r')
+ .replace(/\n/g, '\\n')
+ .replace(/\t/g, '\\t')
+ + "');}return __p.join('');";
+ var func = new Function('obj', tmpl);
+ return data ? func(data) : func;
+ }; |
Aliases: | _.each = _.forEach;
+ _.foldl = _.inject = _.reduce;
+ _.foldr = _.reduceRight;
+ _.select = _.filter;
+ _.all = _.every;
+ _.any = _.some;
+ _.contains = _.include;
+ _.head = _.first;
+ _.tail = _.rest;
+ _.methods = _.functions; |
The OOP Wrapper | |
| 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. | var wrapper = function(obj) { this._wrapped = obj; }; |
| Helper function to continue chaining intermediate results. | var result = function(obj, chain) {
+ return chain ? _(obj).chain() : obj;
+ }; |
| A method to easily add functions to the OOP wrapper. | var addToWrapper = function(name, func) {
+ wrapper.prototype[name] = function() {
+ var args = _.toArray(arguments);
+ unshift.call(args, this._wrapped);
+ return result(func.apply(_, args), this._chain);
+ };
+ }; |
| 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];
+ wrapper.prototype[name] = function() {
+ method.apply(this._wrapped, arguments);
+ return result(this._wrapped, this._chain);
+ };
+ }); |
| Add all accessor Array functions to the wrapper. | each(['concat', 'join', 'slice'], function(name) {
+ var method = ArrayProto[name];
+ wrapper.prototype[name] = function() {
+ return result(method.apply(this._wrapped, arguments), this._chain);
+ };
+ }); |
| Start chaining a wrapped Underscore object. | wrapper.prototype.chain = function() {
+ this._chain = true;
+ return this;
+ }; |
| Extracts the result from a wrapped and chained object. | wrapper.prototype.value = function() {
+ return this._wrapped;
+ };
+
+})();
+
+ |