tightest version so far

lib/is.js

@@ -123,6 +123,18 @@
 
     // OBJECTS
 
+    /**
+     * Is the subject a plain Object?
+     *
+     * @method plainObject
+     * @param {Object} subject, required
+     */
+    plainObject: function(x) {
+      if (!x || is.array(x) || is.bool(x) || is.date(x) || is.func(x) || is.number(x) || is.str(x))
+        return false
+      return !(typeof x == 'number' && isNaN(x))
+    },
+
     /**
      * Is the subject an array?
      *

test/plainObject.js

@@ -0,0 +1,37 @@
+var assert = require('assert')
+var is = require('../lib/is')
+var fn = function(){}
+
+var future = new Date('04/16/9999')
+var today = new Date()
+var past = new Date('04/16/1982')
+
+describe('plainObject', function(){
+
+  it('works', function(){
+    assert.equal(false, is.plainObject(fn), 'fn is wrong')
+    assert.equal(false, is.plainObject(new Date()), 'new Date() is wrong')
+    assert.equal(false, is.plainObject(undefined), 'undefined is wrong')
+    assert.equal(false, is.plainObject(NaN), 'NaN is wrong')
+    assert.equal(false, is.plainObject(null), 'null is wrong')
+    assert.equal(false, is.plainObject(true), 'true is wrong')
+    assert.equal(false, is.plainObject(false), 'false is wrong')
+    assert.equal(true , is.plainObject({}), '{} is wrong')
+    assert.equal(false, is.plainObject([]), '[] is wrong')
+    assert.equal(false, is.plainObject(""), '"" is wrong')
+    assert.equal(false, is.plainObject("  "), '"  " is wrong')
+    assert.equal(false, is.plainObject("asdf"), '"asdf" is wrong')
+    assert.equal(false, is.plainObject("1.23"), '"1.23" is wrong')
+    assert.equal(false, is.plainObject("-42"), '"-42" is wrong')
+    assert.equal(false, is.plainObject("-42.01"), '"-42.01" is wrong')
+    assert.equal(false, is.plainObject("-1"), '"-1" is wrong')
+    assert.equal(false, is.plainObject("0"), '"0" is wrong')
+    assert.equal(false, is.plainObject("666"), '"666" is wrong')
+    assert.equal(false, is.plainObject(1.23), '1.23 is wrong')
+    assert.equal(false, is.plainObject(-42), '-42 is wrong')
+    assert.equal(false, is.plainObject(-1), '-1 is wrong')
+    assert.equal(false, is.plainObject(0), '0 is wrong')
+    assert.equal(false, is.plainObject(666), '666 is wrong')
+  })
+
+})