shrunk down all of the 'is' functions into a single generation, added isRegExp, added a regexp equality test to isEqual, after grayrest's patch

test/objects.js

@@ -37,6 +37,7 @@ $(document).ready(function() {
     ok(!_.isEqual(5, NaN), '5 is not equal to NaN');
     ok(_.isEqual(NaN, NaN), 'NaN is equal to NaN');
     ok(_.isEqual(new Date(100), new Date(100)), 'identical dates are equal');
+    ok(_.isEqual((/hello/ig), (/hello/ig)), 'identical regexes are equal');
   });
 
   test("objects: isEmpty", function() {

test/utility.js

@@ -35,7 +35,7 @@ $(document).ready(function() {
     "compose","defer", "delay", "detect", "each", "every", "extend", "filter", "first",
     "flatten", "foldl", "foldr", "forEach", "functions", "head", "identity", "include",
     "indexOf", "inject", "intersect", "invoke", "isArray", "isDate", "isElement", "isEmpty", "isEqual",
-    "isFunction", "isNaN", "isNull", "isNumber", "isString", "isUndefined", "keys", "last", "lastIndexOf", "map", "max",
+    "isFunction", "isNaN", "isNull", "isNumber", "isRegExp", "isString", "isUndefined", "keys", "last", "lastIndexOf", "map", "max",
     "methods", "min", "pluck", "range", "reduce", "reduceRight", "reject", "rest", "select",
     "size", "some", "sortBy", "sortedIndex", "tail", "template", "toArray", "uniq",
     "uniqueId", "values", "without", "wrap", "zip"];

underscore.js

@@ -30,9 +30,6 @@
   // Export the Underscore object for CommonJS.
   if (typeof exports !== 'undefined') exports._ = _;
 
-  // Maintain a reference to the Object prototype for quick access.
-  var objPro = Object.prototype;
-
   // Current version.
   _.VERSION = '0.4.7';
 
@@ -395,7 +392,7 @@
   _.keys = function(obj) {
     if(_.isArray(obj)) return _.range(0, obj.length);
     var keys = [];
-    for (var key in obj) if (objPro.hasOwnProperty.call(obj, key)) keys.push(key);
+    for (var key in obj) if (Object.prototype.hasOwnProperty.call(obj, key)) keys.push(key);
     return keys;
   };
 
@@ -425,16 +422,22 @@
     if (atype != btype) return false;
     // Basic equality test (watch out for coercions).
     if (a == b) return true;
-    // Check dates' integer values.
-    if (_.isDate(a) && _.isDate(b)) return a.getTime() === b.getTime();
     // 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 true;
+    // 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 (!_.isUndefined(a.length) && a.length !== b.length) return false;
+    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?
@@ -454,31 +457,6 @@
     return !!(obj && obj.nodeType == 1);
   };
 
-  // Is a given value a real Array?
-  _.isArray = function(obj) {
-    return objPro.toString.call(obj) == '[object Array]';
-  };
-
-  // Is a given value a Function?
-  _.isFunction = function(obj) {
-    return objPro.toString.call(obj) == '[object Function]';
-  };
-
-  // Is a given value a String?
-  _.isString = function(obj) {
-    return objPro.toString.call(obj) == '[object String]';
-  };
-
-  // Is a given value a Number?
-  _.isNumber = function(obj) {
-    return objPro.toString.call(obj) == '[object Number]';
-  };
-
-  // Is a given value a Date?
-  _.isDate = function(obj) {
-    return objPro.toString.call(obj) == '[object Date]';
-  };
-
   // 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) {
@@ -495,6 +473,14 @@
     return typeof obj == 'undefined';
   };
 
+  // Define the isArray, isDate, isFunction, isNumber, isRegExp, and
+  // isString functions based on their toString identifiers.
+  _.each(['Array', 'Date', 'Function', 'Number', 'RegExp', 'String'], function(type) {
+    _['is' + type] = function(obj) {
+      return Object.prototype.toString.call(obj) == '[object ' + type + ']';
+    };
+  });
+
   /* -------------------------- Utility Functions: -------------------------- */
 
   // Run Underscore.js in noConflict mode, returning the '_' variable to its