Even though it's not really part of the API, making _.isEmpty work wi…

…th Strings cross-browser.

test/objects.js

@@ -69,6 +69,8 @@ $(document).ready(function() {
     ok(_.isEmpty(new RegExp('')), 'objects with prototype properties are empty');
     ok(_.isEmpty(null), 'null is empty');
     ok(_.isEmpty(), 'undefined is empty');
+    ok(_.isEmpty(''), 'the empty string is empty');
+    ok(!_.isEmpty('moe'), 'but other strings are not');
 
     var obj = {one : 1};
     delete obj.one;

underscore.js

@@ -491,7 +491,7 @@
 
   // Is a given array or object empty?
   _.isEmpty = function(obj) {
-    if (_.isArray(obj)) return obj.length === 0;
+    if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
     for (var key in obj) if (hasOwnProperty.call(obj, key)) return false;
     return true;
   };