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first underscore.js commit -- pulled out from documentcloud's core.js

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commit 02ede85b539a89a44a71ce098f09a9553a3a6890 0 parents
@jashkenas authored
Showing with 368 additions and 0 deletions.
  1. +368 −0 underscore.js
368 underscore.js
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+// Javascript can be so much more pleasant when it's functional -- re-implement
+// a bunch of utility methods from Prototype and Steele's Functional...
+window._ = {
+
+ // The cornerstone, an each implementation.
+ // Handles objects implementing forEach, _each, arrays, and raw objects.
+ each : function(obj, iterator, context) {
+ var index = 0;
+ try {
+ if (obj.forEach) {
+ obj.forEach(iterator, context);
+ } else if (obj.length) {
+ for (var i=0; i<obj.length; i++) {
+ iterator.call(context, obj[i], i);
+ }
+ } else if (obj._each) {
+ obj._each(function(value) {
+ iterator.call(context, value, index++);
+ });
+ } else {
+ var i = 0;
+ for (var key in obj) {
+ var value = obj[key], pair = [key, value];
+ pair.key = key;
+ pair.value = value;
+ iterator.call(context, pair, i++);
+ }
+ }
+ } catch(e) {
+ if (e != '__break__') throw e;
+ }
+ return obj;
+ },
+
+ // Determine whether all of the elements match a truth test. Delegate to
+ // Javascript 1.6's every(), if it is present.
+ all : function(obj, iterator, context) {
+ if (obj.every) return obj.every(iterator, context);
+ var result = true;
+ _.each(obj, function(value, index) {
+ result = result && !!iterator.call(context, value, index);
+ if (!result) throw '__break__';
+ });
+ return result;
+ },
+
+ // Determine if at least one element in the object matches a truth test. Use
+ // Javascript 1.6's some(), if it exists.
+ any : function(obj, iterator, context) {
+ if (obj.some) return obj.some(iterator, context);
+ var result = false;
+ _.each(obj, function(value, index) {
+ if (result = !!iterator.call(context, value, index)) throw '__break__';
+ });
+ return result;
+ },
+
+ // Return the results of applying the iterator to each element. Use Javascript
+ // 1.6's version of map, if possible.
+ map : function(obj, iterator, context) {
+ if (obj.map) return obj.map(iterator, context);
+ var results = [];
+ _.each(obj, function(value, index) {
+ results.push(iterator.call(context, value, index));
+ });
+ return results;
+ },
+
+ // Return the first value which passes a truth test.
+ detect : function(obj, iterator, context) {
+ var result;
+ _.each(obj, function(value, index) {
+ if (iterator.call(context, value, index)) {
+ result = value;
+ throw '__break__';
+ }
+ });
+ return result;
+ },
+
+ // Return all the elements that pass a truth test. Use Javascript 1.6's
+ // filter(), if it exists.
+ select : function(obj, iterator, context) {
+ if (obj.filter) return obj.filter(iterator, context);
+ var results = [];
+ _.each(obj, function(value, index) {
+ if (iterator.call(context, value, index)) results.push(value);
+ });
+ return results;
+ },
+
+ // Determine if a given value is included in the object, based on '=='.
+ include : function(obj, target) {
+ if (_.isArray(obj)) if (obj.indexOf(target) != -1) return true;
+ var found = false;
+ _.each(obj, function(value) {
+ if (value == target) {
+ found = true;
+ throw '__break__';
+ }
+ });
+ return found;
+ },
+
+ // Aka reduce. Inject builds up a single result from a list of values.
+ inject : function(obj, memo, iterator, context) {
+ _.each(obj, function(value, index) {
+ memo = iterator.call(context, memo, value, index);
+ });
+ return memo;
+ },
+
+ // Invoke a method with arguments on every item in a collection.
+ invoke : function(obj, method) {
+ var args = _.toArray(arguments).slice(2);
+ return _.map(obj, function(value) {
+ return (method ? value[method] : value).apply(value, args);
+ });
+ },
+
+ // Return the maximum item or (item-based computation).
+ max : function(obj, iterator, context) {
+ var result;
+ _.each(obj, function(value, index) {
+ value = iterator ? iterator.call(context, value, index) : value;
+ if (result == null || value >= result) result = value;
+ });
+ return result;
+ },
+
+ // Return the minimum element (or element-based computation).
+ min : function(obj, iterator, context) {
+ var result;
+ _.each(obj, function(value, index) {
+ value = iterator ? iterator.call(context, value, index) : value;
+ if (result == null || value < result) result = value;
+ });
+ return result;
+ },
+
+ // Optimized version of a common use case of map: fetching a property.
+ pluck : function(obj, key) {
+ var results = [];
+ _.each(obj, function(value){ results.push(value[key]); });
+ return results;
+ },
+
+ // Return all the elements for which a truth test fails.
+ reject : function(obj, iterator, context) {
+ var results = [];
+ _.each(obj, function(value, index) {
+ if (!iterator.call(context, value, index)) results.push(value);
+ });
+ return results;
+ },
+
+ // Sort the object's values by a criteria produced by an iterator.
+ sortBy : function(obj, iterator, context) {
+ return _.pluck(_.map(obj, function(value, index) {
+ return {
+ value : value,
+ criteria : iterator.call(context, value, index)
+ };
+ }).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, comparator, obj) {
+ var low = 0, high = array.length;
+ while (low < high) {
+ var mid = (low + high) >> 1;
+ comparator(array[mid], obj) < 0 ? low = mid + 1 : high = mid;
+ }
+ return low;
+ },
+
+ // Convert anything iterable into a real, live array.
+ toArray : function(iterable) {
+ if (!iterable) return [];
+ if (_.isArray(iterable)) return iterable;
+ return _.map(iterable, function(val){ return val; });
+ },
+
+ // Return the number of elements in an object.
+ size : function(obj) {
+ _.toArray(obj).length;
+ },
+
+ //------------- The following methods only apply to arrays. -----------------
+
+ // Get the first element of an array.
+ first : function(array) {
+ return array[0];
+ },
+
+ // 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 _.select(array, function(value){ return !!value; });
+ },
+
+ // Return a completely flattened version of an array.
+ flatten : function(array) {
+ return _.inject(array, [], function(memo, value) {
+ if (_.isArray(value)) return memo.concat(_.flatten(value));
+ memo.push(value);
+ return memo;
+ });
+ },
+
+ // Return a version of the array that does not contain the specified value.
+ without : function(array) {
+ var values = array.slice.call(arguments, 0);
+ return _.select(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, sorted) {
+ return _.inject(array, [], function(memo, el, i) {
+ if (0 == i || (sorted ? _.last(memo) != el : !_.include(memo, el))) memo.push(el);
+ return memo;
+ });
+ },
+
+ // Produce an array that contains every item shared between two given arrays.
+ intersect : function(array1, array2) {
+ return _.select(_.uniq(array1), function(item1) {
+ return _.detect(array2, function(item2) { return item1 === item2; });
+ });
+ },
+
+ // If the browser doesn't supply us with indexOf, we might 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.
+ // indexOf : function(array, item) {
+ // var length = array.length;
+ // for (i=0; i<length; i++) if (array[i] === item) return i;
+ // return -1;
+ // }
+
+ /* ---------------- The following methods apply to objects ---------------- */
+
+ // Retrieve the names of an object's properties.
+ keys : function(obj) {
+ return _.pluck(obj, 'key');
+ },
+
+ // Retrieve the values of an object's properties.
+ values : function(obj) {
+ return _.pluck(obj, 'value');
+ },
+
+ // Extend a given object with all of the properties in a source object.
+ extend : function(destination, source) {
+ for (var property in source) destination[property] = source[property];
+ return destination;
+ },
+
+ // Create a (shallow-cloned) duplicate of an object.
+ clone : function(obj) {
+ return _.extend({}, obj);
+ },
+
+ // Is a given value a DOM element?
+ isElement : function(obj) {
+ return !!(obj && obj.nodeType == 1);
+ },
+
+ // Is a given value a real Array?
+ isArray : function(obj) {
+ return Object.prototype.toString.call(obj) == '[object Array]';
+ },
+
+ // Is a given value a Function?
+ isFunction : function(obj) {
+ return typeof obj == 'function';
+ },
+
+ // Is a given variable undefined?
+ isUndefined : function(obj) {
+ return typeof obj == 'undefined';
+ },
+
+ // Convert any value into printable string form.
+ toString : function(obj) {
+ return obj == null ? '' : String(obj);
+ },
+
+ // Create a function bound to a given object (assigning 'this', and arguments,
+ // optionally).
+ bind : function(func, context) {
+ if (!context) return func;
+ var args = _.toArray(arguments).slice(2);
+ return function() {
+ var a = args.concat(_.toArray(arguments));
+ return func.apply(context, a);
+ };
+ },
+
+ // 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() {
+ var args = _.toArray(arguments);
+ var context = args.pop();
+ _.each(args, function(methodName) {
+ context[methodName] = _.bind(context[methodName], context);
+ });
+ },
+
+ // Generate a unique integer id (unique within the entire client session).
+ // Useful for temporary DOM ids.
+ uniqueId : function(prefix) {
+ var id = this._idCounter = (this._idCounter || 0) + 1;
+ return prefix ? prefix + id : id;
+ },
+
+ // 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 at = typeof(a), bt = typeof(b);
+ if (at != bt) return false;
+ // Basic equality test (watch out for coercions).
+ if (a == b) return true;
+ // One of them implements an isEqual()?
+ if (a.isEqual) return a.isEqual(b);
+ // Nothing else worked, deep compare the contents.
+ return at === 'object' && _.isEqualContents(a, b);
+ },
+
+ // Objects have equal contents if they have the same keys, and all the values
+ // are equal (as defined by _.isEqual).
+ _isEqualContents : function(a, b) {
+ var aKeys = _.keys(a), bKeys = _.keys(b);
+ if (aKeys.length != bKeys.length) return false;
+ for (var key in a) if (!_.isEqual(a[key], b[key])) return false;
+ return true;
+ },
+
+ // Javascript templating a-la ERB, pilfered from John Resig's
+ // "Secrets of the Javascript Ninja", page 83.
+ template : function(str, data) {
+ var fn = new Function('obj',
+ 'var p=[],print=function(){p.push.apply(p,arguments);};' +
+ 'with(obj){p.push(\'' +
+ str
+ .replace(/[\r\t\n]/g, " ")
+ .split("<%").join("\t")
+ .replace(/((^|%>)[^\t]*)'/g, "$1\r")
+ .replace(/\t=(.*?)%>/g, "',$1,'")
+ .split("\t").join("');")
+ .split("%>").join("p.push('")
+ .split("\r").join("\\'")
+ + "');}return p.join('');");
+ return data ? fn(data) : fn;
+ }
+
+};
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