merging mrjjwright's isBoolean, with tests, docs, and credit

README

@@ -28,3 +28,4 @@ Many thanks to our contributors:
   Jed Schmidt
   Noah Sloan
   Luke Sutton
+  John Wright

index.html

@@ -162,7 +162,7 @@
       <a href="#functions">functions</a>, <a href="#extend">extend</a>, <a href="#clone">clone</a>, <a href="#tap">tap</a>,
       <a href="#isEqual">isEqual</a>, <a href="#isEmpty">isEmpty</a>, <a href="#isElement">isElement</a>,
       <a href="#isArray">isArray</a>, <a href="#isArguments">isArguments</a>, <a href="#isFunction">isFunction</a>, <a href="#isString">isString</a>,
-      <a href="#isNumber">isNumber</a>, <a href="#isDate">isDate</a>, <a href="#isRegExp">isRegExp</a>
+      <a href="#isNumber">isNumber</a>, <a href="#isBoolean">isBoolean</a>, <a href="#isDate">isDate</a>, <a href="#isRegExp">isRegExp</a>
       <a href="#isNaN">isNaN</a>, <a href="#isNull">isNull</a>,
       <a href="#isUndefined">isUndefined</a>
       </span>
@@ -874,6 +874,16 @@ _.isFunction("moe");
       <pre>
 _.isNumber(8.4 * 5);
 =&gt; true
+</pre>
+
+      <p id="isBoolean">
+        <b class="header">isBoolean</b><code>_.isBoolean(object)</code>
+        <br />
+        Returns <i>true</i> if <b>object</b> is either <i>true</i> or <i>false</i>.
+      </p>
+      <pre>
+_.isBoolean(null);
+=&gt; false
 </pre>
 
       <p id="isDate">

test/objects.js

@@ -14,7 +14,7 @@ $(document).ready(function() {
     var expected = ["all", "any", "bind", "bindAll", "breakLoop", "clone", "compact",
     "compose","defer", "delay", "detect", "each", "every", "extend", "filter", "first",
     "flatten", "foldl", "foldr", "forEach", "functions", "head", "identity", "include",
-    "indexOf", "inject", "intersect", "invoke", "isArguments", "isArray", "isDate", "isElement", "isEmpty", "isEqual",
+    "indexOf", "inject", "intersect", "invoke", "isArguments", "isArray", "isBoolean", "isDate", "isElement", "isEmpty", "isEqual",
     "isFunction", "isNaN", "isNull", "isNumber", "isRegExp", "isString", "isUndefined", "keys", "last", "lastIndexOf", "map", "max",
     "methods", "min", "mixin", "noConflict", "pluck", "range", "reduce", "reduceRight", "reject", "rest", "select",
     "size", "some", "sortBy", "sortedIndex", "tail", "tap", "template", "times", "toArray", "uniq",
@@ -136,6 +136,8 @@ $(document).ready(function() {
     ok(!_.isBoolean("true"), 'the string "true" is not a boolean');
     ok(!_.isBoolean(arguments), 'the arguments object is not a boolean');
     ok(!_.isBoolean(undefined), 'undefined is not a boolean');
+    ok(!_.isBoolean(NaN), 'NaN is not a boolean');
+    ok(!_.isBoolean(null), 'null is not a boolean');
     ok(_.isBoolean(true), 'but true is');
     ok(_.isBoolean(false), 'and so is false');
     ok(_.isBoolean(iBoolean), 'even from another frame');

underscore.js

@@ -527,7 +527,7 @@
 
   // Is a given value a boolean?
   _.isBoolean = function(obj) {
-    return (toString.call(obj) === '[object Boolean]');
+    return obj === true || obj === false;
   };
 
   // Is a given value a date?